Calponin family repeat;

                          10        20
                  ....*....|....*....|....*
gi 116283891  174 IGLQMGTNRGASQAGMTGYGMPRQI 198
Cdd:pfam00402   1 IGLQMGTNKGASQSGMTAFGAVRHI 25

Calponin homology (CH) domain; The CH domain is found in both cytoskeletal proteins and signal transduction proteins. The CH domain is involved in actin binding in some members of the family. However in calponins there is evidence that the CH domain is not involved in its actin binding activity. Most member proteins have from two to four copies of the CH domain, however some proteins such as calponin have only a single copy.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891   24 ADLEQILIQWITTQCREDVgqPQPGRENFQKWLKDGTVLCKLINSLYPEGqapVKKIQASSMAFKQMEQISQFLQAAER- 102
Cdd:pfam00307   1 LELEKELLRWINSHLAEYG--PGVRVTNFTTDLRDGLALCALLNKLAPGL---VDKKKLNKSEFDKLENINLALDVAEKk 75

                          90       100       110
                  ....*....|....*....|....*....|.
gi 116283891  103 YGINTTDIfQTVDLWEGKNMaCVQRTLMNLG 133
Cdd:pfam00307  76 LGVPKVLI-EPEDLVEGDNK-SVLTYLASLF 104

Calponin homology domain; Actin binding domains present in duplicate at the N-termini of spectrin-like proteins (including dystrophin, alpha-actinin). These domains cross-link actin filaments into bundles and networks. A calponin homology domain is predicted in yeasst Cdc24p.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891    29 ILIQWITTQCREDvgqPQPGRENFQKWLKDGTVLCKLINSLYPeGQAPVKKIQASSMAFKQMEQISQFLQAAERYGINtT 108
Cdd:smart00033   2 TLLRWVNSLLAEY---DKPPVTNFSSDLKDGVALCALLNSLSP-GLVDKKKVAASLSRFKKIENINLALSFAEKLGGK-V 76

                           90       100
                   ....*....|....*....|....*
gi 116283891   109 DIFQTVDLWEG-KNMACVQRTLMNL 132
Cdd:smart00033  77 VLFEPEDLVEGpKLILGVIWTLISL 101

calponin homology (CH) domain found in the transgelin family; The transgelin (TAGLN) family includes transgelin, transgelin-2 and transgelin-3. Transgelin, also called 22 kDa actin-binding protein, protein WS3-10, or smooth muscle protein 22-alpha (SM22-alpha), acts as an actin cross-linking/gelling protein that may be involved in calcium interactions and in regulating contractile properties of the cell. Transgelin-2, also called epididymis tissue protein Li 7e, or SM22-alpha homolog, acts as an actin-binding protein that induces actin gelation and regulates actin cytoskeleton. It may participate in the development and progression of multiple cancers. Transgelin-3, also called neuronal protein 22 (NP22), or neuronal protein NP25, may have a role in alcohol-related adaptations and may mediate regulatory signal transduction pathways in neurons. Members of this family contain a single copy of the CH domain. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  23 DADLEQILIQWITTQCREDVGQPQPGRENFQKWLKDGTVLCKLINSLYPEGQAPVKKIQASSMAFKQMEQISQFLQAAER 102
Cdd:cd21209    1 DPELESRLVEWIVAQCGSDVGRPDPGRLGFQKWLKDGTVLCKLINSLYPEGSKPVKKIQSSKMAFKQMEQISQFLKAAED 80

                         90       100       110
                 ....*....|....*....|....*....|....*....
gi 116283891 103 YGINTTDIFQTVDLWEGKNMACVQRTLMNLGGLAVARDD 141
Cdd:cd21209   81 YGVRTTDIFQTVDLWEGKDMAAVQRTLMALGSLAVTKDD 119

calponin homology (CH) domain found in transgelin; Transgelin, also called 22 kDa actin-binding protein, protein WS3-10, or smooth muscle protein 22-alpha (SM22-alpha), acts as an actin cross-linking/gelling protein that may be involved in calcium interactions and in regulating contractile properties of the cell. It may also contribute to replicative senescence. Transgelin contains a single copy of the CH domain. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  23 DADLEQILIQWITTQCREDVGQPQPGRENFQKWLKDGTVLCKLINSLYPEGQAPVKKIQAS-SMAFKQMEQISQFLQAAE 101
Cdd:cd21279    1 DEELEERLVEWIVVQCGPDVGRPDRGRLGFQVWLKNGVVLSKLVNSLYPDGSKPVKIPDNPpSMVFKQMEQVAQFLKAAE 80

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|.
gi 116283891 102 RYGINTTDIFQTVDLWEGKNMACVQRTLMNLGGLAVARDDG 142
Cdd:cd21279   81 DYGVVKTDMFQTVDLYEGKDMAAVQRTLVALGSLAVTKNDG 121

calponin homology (CH) domain superfamily; CH domains are actin filament (F-actin) binding motifs, which may be present as a single copy or in tandem repeats (which increase binding affinity). They either function as autonomous actin binding motifs or serve a regulatory function. CH domains are found in cytoskeletal and signal transduction proteins, including actin-binding proteins like spectrin, alpha-actinin, dystrophin, utrophin, and fimbrin, as well as proteins essential for regulation of cell shape (cortexillins), and signaling proteins (Vav).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  27 EQILIQWITTQCREDVGQPqpgRENFQKWLKDGTVLCKLINSLYPEgqAPVKKIQASSMAFKQMEQISQFLQAAERYGIN 106
Cdd:cd00014    1 EEELLKWINEVLGEELPVS---ITDLFESLRDGVLLCKLINKLSPG--SIPKINKKPKSPFKKRENINLFLNACKKLGLP 75

                         90       100
                 ....*....|....*....|....*..
gi 116283891 107 TTDIFQTVDLWEGKNMACVQRTLMNLG 133
Cdd:cd00014   76 ELDLFEPEDLYEKGNLKKVLGTLWALA 102

Calponin homology (CH) domain; The CH domain is found in both cytoskeletal proteins and signal transduction proteins. The CH domain is involved in actin binding in some members of the family. However in calponins there is evidence that the CH domain is not involved in its actin binding activity. Most member proteins have from two to four copies of the CH domain, however some proteins such as calponin have only a single copy.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891   24 ADLEQILIQWITTQCREDVgqPQPGRENFQKWLKDGTVLCKLINSLYPEGqapVKKIQASSMAFKQMEQISQFLQAAER- 102
Cdd:pfam00307   1 LELEKELLRWINSHLAEYG--PGVRVTNFTTDLRDGLALCALLNKLAPGL---VDKKKLNKSEFDKLENINLALDVAEKk 75

                          90       100       110
                  ....*....|....*....|....*....|.
gi 116283891  103 YGINTTDIfQTVDLWEGKNMaCVQRTLMNLG 133
Cdd:pfam00307  76 LGVPKVLI-EPEDLVEGDNK-SVLTYLASLF 104

Calponin homology domain; Actin binding domains present in duplicate at the N-termini of spectrin-like proteins (including dystrophin, alpha-actinin). These domains cross-link actin filaments into bundles and networks. A calponin homology domain is predicted in yeasst Cdc24p.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891    29 ILIQWITTQCREDvgqPQPGRENFQKWLKDGTVLCKLINSLYPeGQAPVKKIQASSMAFKQMEQISQFLQAAERYGINtT 108
Cdd:smart00033   2 TLLRWVNSLLAEY---DKPPVTNFSSDLKDGVALCALLNSLSP-GLVDKKKVAASLSRFKKIENINLALSFAEKLGGK-V 76

                           90       100
                   ....*....|....*....|....*
gi 116283891   109 DIFQTVDLWEG-KNMACVQRTLMNL 132
Cdd:smart00033  77 VLFEPEDLVEGpKLILGVIWTLISL 101

calponin homology (CH) domain found in the calponin family; Calponin is an actin filament-associated regulatory protein expressed in smooth muscle and many types of non-muscle cells. There are three calponin isoforms, calponin-1, -2, -3. All of them are actin-binding proteins with functions in inhibiting actin-activated myosin ATPase and stabilizing the actin cytoskeleton. Calponin-1 is specifically expressed in smooth muscle cells and plays a role in fine-tuning smooth muscle contractility. Calponin-2 is expressed in both smooth muscle and non-muscle cells and regulates multiple actin cytoskeleton-based functions. Calponin-3 is expressed in the brain and participates in actin cytoskeleton-based activities in embryonic development and myogenesis. Members of this family contain a single copy of the CH domain. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  23 DADLEQILIQWITTQCREDVGQpqpgreNFQKWLKDGTVLCKLINSLYPegqAPVKKIQASSMAFKQMEQISQFLQAAER 102
Cdd:cd21211    1 DHQKEAELRTWIEGVTGLSIGP------NFQKGLKDGIILCELINKLQP---GSVKKINESMQNWHQLENIGNFIKAIVS 71

                         90       100       110
                 ....*....|....*....|....*....|....
gi 116283891 103 YGINTTDIFQTVDLWEGKNMACVQRTLMNLGGLA 136
Cdd:cd21211   72 YGMKPHDIFEANDLFENGNMTQVQVTLLALAGKA 105

calponin homology (CH) domain found in calponin-1 and similar proteins; Calponin-1 (CNN1), also called basic calponin, or smooth muscle calponin H1, is a thin filament-associated protein that is implicated in the regulation and modulation of smooth muscle contraction. It is capable of binding to actin, calmodulin, troponin C, and tropomyosin. Calponin-1 contains a single copy of the CH domain. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  23 DADLEQILIQWITTQCREDVGqpqpgrENFQKWLKDGTVLCKLINSLYPegqAPVKKIQASSMAFKQMEQISQFLQAAER 102
Cdd:cd21282    1 DPQTEEELRVWIEGVTGRRIG------DNFMDGLKDGVILCELINKLQP---GSVRKINESTQNWHKLENIGNFIKAIMH 71

                         90       100       110
                 ....*....|....*....|....*....|....
gi 116283891 103 YGINTTDIFQTVDLWEGKNMACVQRTLMNLGGLA 136
Cdd:cd21282   72 YGVKPHDIFEANDLFENTNHTQVQSTLIALASMA 105

Calponin family repeat;

                          10        20
                  ....*....|....*....|....*
gi 116283891  174 IGLQMGTNRGASQAGMTGYGMPRQI 198
Cdd:pfam00402   1 IGLQMGTNKGASQSGMTAFGAVRHI 25

calponin homology (CH) domain found in VAV proteins; VAV proteins function both as cytoplasmic guanine nucleotide exchange factors (GEFs) for Rho GTPases and as scaffold proteins, and they play important roles in cell signaling by coupling cell surface receptors to various effector functions. They play key roles in processes that require cytoskeletal reorganization including immune synapse formation, phagocytosis, cell spreading, and platelet aggregation, among others. Vertebrates have three VAV proteins (VAV1, VAV2, and VAV3). VAV proteins contain several domains that enable their function: N-terminal calponin homology (CH), acidic, RhoGEF (also called Dbl-homologous or DH), Pleckstrin Homology (PH), C1 (zinc finger), SH2, and two SH3 domains. This model corresponds to the CH domain, an actin-binding domain which is present as a single copy in VAV proteins.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 116283891  56 LKDGTVLCKLINSLYPEGQAPVKKIQASSMA-FKQMEQISQFLQAA-ERYGINTTDIFQTVDLWEGKNMACVQRTL 129
Cdd:cd21201   36 LRDGVLLCQLLNRLSPGSVDDREINLRPQMSqFLCLKNIRTFLQACrTVFGLRSADLFEPEDLYDVTNFGKVIRTL 111

calponin homology (CH) domain found in the growth arrest-specific protein 2 family; The growth arrest-specific protein 2 (GAS-2) family includes GAS-2, and GAS-2 like proteins, GAS2L1-3. GAS-2 may play a role in apoptosis by acting as a cell death substrate for caspases. GAS2L1 (also called GAS2-related protein on chromosome 22 or growth arrest-specific protein 2-like 1) and GAS2L2 (also called GAS2-related protein on chromosome 17 or growth arrest-specific protein 2-like 2) may be involved in the cross-linking of microtubules and microfilaments. GAS2L3, also called GAS2-like protein 3, is a cytoskeletal linker protein that may promote and stabilize the formation of the actin and microtubule network. Members of this family contain a single copy of the CH domain at the N-terminal region. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  38 CREDVGQ-------PQPGRENFQKWLKDGTVLCKLINSL-----------YPEGQAPVKKIQ----ASSMAFKQMEQISQ 95
Cdd:cd21204    7 MKEDLAEwlndllgDDLTPDNFLDELRNGVVLCQLAQKIqeaaekareagKKNGPPPSYKLKcnenAKPGSFFARDNVAN 86

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|....
gi 116283891  96 FLQAAERYGINTTDIFQTVDLWEGKNMACVQRTLMNLGGLAVAR 139
Cdd:cd21204   87 FLRWCRKLGVDEVLLFESEDLVLHKNPRQVLLCLLELARIAARY 130

calponin homology (CH) domain found in LIM domain only protein 7; LIM domain only protein 7 (LMO-7), also called F-box only protein 20, or LOMP, is a transcription regulator for expression of many Emery-Dreifuss muscular dystrophy (EDMD)-relevant genes. It binds to alpha-actinin and AF6/afadin at adherens junctions for epithelial cell-cell adhesion. It contains a single copy of the CH domain at the N-terminus. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  40 EDVGQPQPGRENFQKWLKDGTVLCKLINSLYPegqAPVKKIQASSMAFKQMEQISQFLQAAERYGINTTDIFQTVDLWEG 119
Cdd:cd21277   10 EAVTGKNFGNKDFRSALENGVLLCDLINKIKP---GIIKKINRLSTPIAGLDNINVFLKACEKLGLKEAQLFHPGDLQDL 86

                 ....*...
gi 116283891 120 KNMACVQR 127
Cdd:cd21277   87 STRVTVKQ 94

calponin homology (CH) domain found in alpha-Pak Interactive eXchange factor; Alpha-Pak Interactive eXchange factor (alpha-PIX), also called PAK-interacting exchange factor alpha, Rho guanine nucleotide exchange factor 6 (ARHGEF6), Rac/Cdc42 guanine nucleotide exchange factor 6, or Cool (Cloned out of Library)-2, activates small GTPases by exchanging bound GDP for free GTP. It acts as a GEF for both Cdc42 and Rac1, and is localized in dendritic spines where it regulates spine morphogenesis. It controls dendritic length and spine density in the hippocampus. Mutations in the ARHGEF6 gene cause X-linked intellectual disability in humans. Alpha-PIX contains a single copy of the CH domain at its N-terminus. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  50 ENFQKW-LKDGTVLCKLINSLYPEGQAPV---KKIQASSmafkqMEQISQFLQAAERYGInttDIFQTVDLWEGKNMACV 125
Cdd:cd21265   28 EEFLKSsLKDGVVLCKLIERLLPGSVEKYclePKTEADC-----IGNIKEFLKGCAALKV---ETFEPDDLYTGENFSKV 99

                 ....
gi 116283891 126 QRTL 129
Cdd:cd21265  100 LSTL 103

first calponin homology (CH) domain found in the plastin/fimbrin family; This family includes plastin and fimbrin. Plastin has three isoforms, plastin-1, -2, and -3, which are all actin-bundling proteins. Plastin-1, also called intestine-specific plastin, or I-plastin, is an actin-bundling protein in the absence of calcium. Plastin-2, also called L-plastin, LC64P, or lymphocyte cytosolic protein 1 (LCP-1), plays a role in the activation of T-cells in response to costimulation through TCR/CD3 and CD2 or CD28. It modulates the cell surface expression of IL2RA/CD25 and CD69. Plastin-3, also called T-plastin, is found in intestinal microvilli, hair cell stereocilia, and fibroblast filopodia. It may play a role in the regulation of bone development. Fimbrin has been found in plants and fungi. Arabidopsis thaliana fimbrin (AtFIM) includes fimbrin-1, -2, -3, -4, and -5; they cross-link actin filaments (F-actin) in a calcium independent manner. They stabilize and prevent F-actin depolymerization mediated by profilin. They act as key regulators of actin cytoarchitecture, probably involved in cell cycle, cell division, cell elongation and cytoplasmic tractus. AtFIM5 is an actin bundling factor that is required for pollen germination and pollen tube growth. Fungal fimbrin binds to actin, and functionally associates with actin structures involved in the development and maintenance of cell polarity. Members of this family contain four copies of the CH domain. This model corresponds to the first CH domain. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  23 DADLEQILIqwittqcredvgqPQPGRENFQKWLKDGTVLCKLINSLYPeGQAPVKKIQASSM--AFKQMEQISQFLQAA 100
Cdd:cd21217   17 DPDLKHLLP-------------IDPDGDDLFEALRDGVLLCKLINKIVP-GTIDERKLNKKKPknIFEATENLNLALNAA 82

                         90       100
                 ....*....|....*....|
gi 116283891 101 ERYGINTTDIfQTVDLWEGK 120
Cdd:cd21217   83 KKIGCKVVNI-GPQDILDGN 101

calponin homology (CH) domain found in the leucine-rich repeat and calponin homology domain-containing protein family; The leucine-rich repeat and calponin homology domain-containing protein (LRCH) family includes LRCH1-4. LRCH1, also called calponin homology domain-containing protein 1, or neuronal protein 81 (NP81), acts as a negative regulator of GTPase Cdc42 by sequestering Cdc42-guanine exchange factor DOCK8. LRCH2 may play a role in the organization of the cytoskeleton. LRCH3 is part of the DISP complex and may regulate the association of septins with actin and thereby regulate the actin cytoskeleton. LRCH4, also called leucine-rich repeat neuronal protein 4, or leucine-rich neuronal protein, acts as a novel Toll-like receptor (TLR) accessory protein that regulates the innate immune response. Members of this family contain a single copy of the CH domain at the C-terminus. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  56 LKDGTVLCKLINSLYP-------EGQAPVKKIqasSMAfKQMEQISQFLQAAERYGINTTDIFQTVDLWEGKNMACVQRT 128
Cdd:cd21205   26 LMDGVVLCHLANHVRPrsvpsihVPSPAVPKL---SMA-KCRRNVENFLEACRKLGVPEERLCSPGDILEEKGLVRVAVT 101

                 ....
gi 116283891 129 LMNL 132
Cdd:cd21205  102 VQAL 105

calponin homology (CH) domain found in beta-Pak Interactive eXchange factor; Beta-Pak Interactive eXchange factor (beta-PIX), also called PAK-interacting exchange factor beta, Rho guanine nucleotide exchange factor 7 (ARHGEF7), p85, or Cool (Cloned out of Library)-1, activates small GTPases by exchanging bound GDP for free GTP. It acts as a GEF for both Cdc42 and Rac1, and plays important roles in regulating neuroendocrine exocytosis, focal adhesion maturation, cell migration, synaptic vesicle localization, and insulin secretion. Beta-PIX contains a single copy of the CH domain at its N-terminus. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  27 EQILIQWITTQCREDVGQPQPGRENF-QKWLKDGTVLCKLINSLYPegqAPVKKI-QASSMAFKQMEQISQFLQAAERYG 104
Cdd:cd21266    3 EQTVTWLITLGVLESPKKTISDPEGFlQASLKDGVVLCRLLERLLP---GSIDKVyPEPRTESECLSNIREFLRGCGALR 79

                         90       100
                 ....*....|....*....|....*...
gi 116283891 105 INTtdiFQTVDLWEGKNMACVQRTLMNL 132
Cdd:cd21266   80 LET---FDANDLYQGQNFNKVLSSLVAL 104

calponin homology (CH) domain found in leucine-rich repeat and calponin homology domain-containing protein 4; Leucine-rich repeat and calponin homology domain-containing protein 4 (LRCH4), also called leucine-rich repeat neuronal protein 4, or leucine-rich neuronal protein, acts as a novel Toll-like receptor (TLR) accessory protein that regulates the innate immune response. LRCH4 contains a single copy of the CH domain at the C-terminus. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  50 ENFQKWLKDGTVLCKLINSLYPEGqapVKKIQASSMAF------KQMEQISQFLQAAERYGINTTDIFQTVDLWEgKNMA 123
Cdd:cd21273   23 EDLAEALSNGAVLCQLANQLRPRS---VSIIHVPSPAVpklskaKCRKNVENFIEACRKMGVPEVDLCSPSDVLL-QGPA 98

                 ....*....
gi 116283891 124 CVQRTLMNL 132
Cdd:cd21273   99 AVLRTVLAL 107

calponin homology (CH) domain found in leucine-rich repeat and calponin homology domain-containing protein 3; Leucine-rich repeat and calponin homology domain-containing protein 3 (LRCH3) is part of the DISP (DOCK7-Induced Septin disPlacement) complex. It may regulate the association of septins with actin and thereby regulate the actin cytoskeleton. LRCH3 contains a single copy of the CH domain at the C-terminus. CH domains are actin filament (F-actin) binding motifs.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  56 LKDGTVLCKLINSLYPEG----QAPVKKIQASSMAfKQMEQISQFLQAAERYGINTTDIFQTVDLWEGKNMACVQRTLMN 131
Cdd:cd21272   26 LTDGVVLCHLANHVRPRSvpsiHVPSPAVPKLTMA-KCRRNVENFLEACRRIGVPQEQLCLPLHILEEKGLSQVAVTVQA 104

                 ....*
gi 116283891 132 LGGLA 136
Cdd:cd21272  105 LLELA 109

calponin homology (CH) domain found in Ras GTPase-activating-like protein IQGAP1; IQ motif containing GTPase activating protein 1 (IQGAP1), also called p195, is a homodimeric protein that is widely expressed among vertebrate cell types from early embryogenesis. It plays a crucial role in regulating the dynamics and assembly of the actin cytoskeleton. It belongs to the IQGAP family, which consists of multi-domain proteins having a calponin-homology (CH) domain which binds F-actin, IQGAP-specific repeats, a single WW domain, four IQ motifs that mediate interactions with calmodulin, and a RasGAP related domain that binds active Rho family GTPases. IQGAP1 negatively regulates Ras family GTPases by stimulating their intrinsic GTPase activity. It lacks GAP activity. Both, IQGAP1 and IQGAP2, specifically bind to Cdc42 and Rac1, but not to RhoA. Despite similarities to part of the sequence of RasGAP, neither IQGAP1 nor IQGAP2 interacts with Ras. IQGAP1 contains a single copy of the CH domain at the N-terminus.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 116283891  16 QKIEKQYDADLEQILiQWITTQCREDVgqpqPGRENFQKWLKDGTVLCKLINSLYPEgQAPVKKI--------QASSMAF 87
Cdd:cd21274    1 QNVAYEYLCHLEEAK-RWMEACLGEDL----PPTTELEEGLRNGVYLAKLGNFFSPK-VVSLKKIydreqtryKATGLHF 74

                         90       100       110
                 ....*....|....*....|....*....|....*
gi 116283891  88 KQMEQISQFLQAAERYGINTTDIFQTVDLWEGKNM 122
Cdd:cd21274   75 RHTDNVIQWLNAMDEIGLPKIFYPETTDIYDRKNM 109