protein kinase C conserved region 1 (C1 domain) found in the unconventional myosin-IX family
Myosins IX (Myo9) is a class of unique motor proteins with a common structure of an N-terminal extension preceding a myosin head homologous to the Ras-association (RA) domain, a head (motor) domain, a neck with IQ motifs that bind light chains, and a C-terminal tail containing cysteine-rich zinc binding (C1) and Rho-GTPase activating protein (RhoGAP) domains. There are two genes for myosins IX in humans, IXa and IXb, that are different in their expression and localization. IXa is expressed abundantly in brain and testis, and IXb is expressed abundantly in tissues of the immune system. 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.