Alternative titles; symbols
HGNC Approved Gene Symbol: CIBAR2
Cytogenetic location: 16q24.1 Genomic coordinates (GRCh38): 16:85,098,358-85,112,472 (from NCBI)
Proteins containing a Bin/amphiphysin (600418)/Rvs (BAR) domain, such as FAM92B, are predicted to bind lipid membranes and generate membrane curvature. BAR domain proteins function as homo- or heterodimers in endocytosis, vesicle fission and fusion, and regulation of the actin cytoskeleton (summary by Li et al., 2016).
Using tandem affinity purification and mass spectrometry to identify binding partners of the ciliary protein CBY1 (607757) in HEK293 cells, Li et al. (2016) identified FAM92A (CIBAR1; 617273) and FAM92B. The deduced 304-amino acid FAM92B protein is predominantly made up of a BAR domain and has a calculated molecular mass of 35 kD. Database analysis indicated FAM92B expression predominantly in multiciliated tissues such as trachea, lung, and fallopian tube. Epitope-tagged FAM92A and FAM92B colocalized with CBY1 at the base of primary cilia in human retinal pigment epithelial cells and in multiciliated mouse tracheal epithelial cells. The FAM92 proteins also showed punctate vesicular distribution. Database analysis revealed orthologs of FAM92B in vertebrates only.
Using human HEK293 cells, Li et al. (2016) found that CBY1 interacted with FAM92A and FAM92B. Immunoprecipitation analysis detected interaction of both FAM92 proteins with CBY1 in transfected HEK293T cells. Mutation analysis revealed that both the N-terminal region and C-terminal coiled-coil motif of CBY1 interacted with the BAR domains of FAM92 proteins. Knockdown studies showed that FAM92 proteins and CYB1 at least partly stabilized each other. Coexpression of FAM92A with CYB1 induced formation of large globular-like membranes, whereas coexpression of FAM92B with CYB1 induced formation of membrane tubule-like structures. Both membrane structures contained RAB8 (see RAB8A, 165040). Li et al. (2016) proposed that FAM92 proteins cooperate with CBY1 in recruitment and fusion of endosomal vesicles at distal appendages during early stages of ciliogenesis.
Hartz (2016) mapped the FAM92B gene to chromosome 16q24.1 based on an alignment of the FAM92B sequence (GenBank AK126284) with the genomic sequence (GRCh38).
Hartz, P. A. Personal Communication. Baltimore, Md. 12/22/2016.
Li, F.-Q., Chen, X., Fisher, C., Siller, S. S., Zelikman, K., Kuriyama, R., Takemaru, K.-I. BAR domain-containing FAM92 proteins interact with Chibby1 to facilitate ciliogenesis. Molec. Cell. Biol. 36: 2668-2680, 2016. [PubMed: 27528616] [Full Text: https://doi.org/10.1128/MCB.00160-16]