protein kinase C conserved region 1 (C1 domain) found in unconventional myosin-IXb and similar proteins
Myosin-IXb, also called unconventional myosin-9b (Myo9b), is an actin-dependent motor protein of the unconventional myosin IX class. It is expressed abundantly in tissues of the immune system, like lymph nodes, thymus, and spleen, and in several immune cells including dendritic cells, macrophages and CD4+ T cells. Myosin-IXb contains a Ras-associating (RA) domain, a motor domain, a protein kinase C conserved region 1 (C1), and a Rho GTPase activating (RhoGAP) domain. Myosin-IXb acts as a motorized signaling molecule that links Rho signaling to the dynamic actin cytoskeleton. It regulates leukocyte migration by controlling RhoA signaling. Myosin-IXb is also involved in the development of autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, and type 1 diabetes. Moreover, Myosin-IXb is a ROBO-interacting protein that suppresses RhoA activity in lung cancer cells. This model corresponds to the C1 domain. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.
Jiyao W et al.(2023). "The conserved domain database in 2023.",