PROSITE documentation PDOC00772

CRISP family signature

A variety of extracellular proteins from eukaryotes have been found to be evolutionary related. They have been termed cysteine-rich secretory proteins (CRISP). Some relevant members of this family are:

• Rodent sperm-coating glycoprotein (SCP), also known as acidic epididymal glycoprotein (AEG) . This protein is thought to be involved in sperm maturation [1]. It is a protein of about 220 residues and probably contains eight disulfide bonds.
• Mammalian testis-specific protein Tpx-1 [2]. Tpx-1 is highly related to SCP's.
• Mammalian glioma pathogenesis-related protein (GliPR).
• Lizard helothermine, a toxin that blocks ryanodine receptors.
• Venom allergen 5 (Ag5) from vespid wasps and venom allergen 3 (Ag3) from fire ants. These proteins are potent allergens and are the main cause of allergic reactions to stings from insects of the hymenoptera family [3]. Ag5/3 are proteins of about 200 residues and contain four disulfide bonds.
• Plant pathogenesis proteins of the PR-1 family [4]. These proteins are synthesized during pathogen infection or other stress-related responses. They are proteins of about 130 to 140 residues and probably contain three disulfide bonds.
• Proteins Sc7 and Sc14 from the basidomycete fungus Schizophyllum commune. These extracellular proteins are loosely associated with fruit body hyphal walls [5]. Sc7/14 are proteins of about 180 residues and probably contain two disulfide bonds.
• Ancylostoma secreted protein from dog hookworm.
• Yeast hypothetical proteins YJL078c, YJL079c and YKR013w.

The exact function of these proteins is not yet known. As signature patterns, we selected two conserved regions located in their C-terminal half. The second signature contains a cysteine which is known to be involved in a disulfide bond in Ag5.