Protein Domain : Cysteine-rich secretory protein, SCP domain IPR034117

Type	Domain
Description	This SCP-like extracellular protein domain is found in cysteine-rich secretory proteins (CRISPs). Involvement of CRISP in response to pathogens, fertilization, and sperm maturation have been proposed [ , , ]. One member, Tex31 from the venom duct of Conus textile, has been shown to possess proteolytic activity sensitive to serine protease inhibitors []. SCP has also been proposed to be a Ca2 chelating serine protease. The Ca2-chelating function would fit with various signaling processes that members of this family, such as the CRISPs, are involved in, and is supported by sequence and structural evidence of a conserved pocket containing two histidines and a glutamate. It also may explain how helothermine, a toxic peptide secreted by the beaded lizard, blocks Ca++ transporting ryanodine receptors []. One member, DE or CRISP-1, has been shown to mediate gamete fusion by binding to the egg surface; a sequence motif in the SCP domain plays a role in that binding [].The SCP domain is also known as CAP domain [ ]. The wider family of SCP containing proteins includes plant pathogenesis-related protein 1 (PR-1), CRISPs, mammalian cysteine-rich secretory proteins, which combine SCP with a C-terminal cysteine rich domain, and allergen 5 from vespid venom. It has been proposed that SCP domains may function as endopeptidases.
Short Name	SCP_CRISP