protein kinase C conserved region 1 (C1 domain) found in RAS guanyl-releasing protein 3 (RASGRP3) and similar proteins
RASGRP3, also called calcium and DAG-regulated guanine nucleotide exchange factor III (CalDAG-GEFIII), or guanine nucleotide exchange factor for Rap1, is a guanine nucleotide-exchange factor activating H-Ras, R-Ras and Ras-associated protein-1/2. It functions as an important mediator of signaling downstream from receptor coupled phosphoinositide turnover in B and T cells. 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.