protein kinase C conserved region 1 (C1 domain) found in A-kinase anchor protein 13 (AKAP-13) and similar proteins
AKAP-13, also called AKAP-Lbc, breast cancer nuclear receptor-binding auxiliary protein (Brx-1), guanine nucleotide exchange factor Lbc, human thyroid-anchoring protein 31, lymphoid blast crisis oncogene (LBC oncogene), non-oncogenic Rho GTPase-specific GTP exchange factor, protein kinase A-anchoring protein 13 (PRKA13), or p47, is a scaffold protein that plays an important role in assembling signaling complexes downstream of several types of G protein-coupled receptors (GPCRs). It activates RhoA in response to GPCR signaling via its function as a Rho guanine nucleotide exchange factor. It may also activate other Rho family members. AKAP-13 plays a role in cell growth, cell development and actin fiber formation. Its Rho-GEF activity is regulated by protein kinase A (PKA), through binding and phosphorylation. Alternative splicing of this gene in humans has at least 3 transcript variants encoding different isoforms (i.e. proto-/onco-Lymphoid blast crisis, Lbc and breast cancer nuclear receptor-binding auxiliary protein, and Brx) that contain a C1 domain followed by a dbl oncogene homology (DH) domain and a PH domain which are required for full transforming activity. 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.