Pathways & interactions
CAP superfamily (IPR035940)
Short name: CAP_sf
- Cysteine-rich secretory protein, allergen V5/Tpx-1-related (IPR001283)
- Ves allergen (IPR002413)
- CAP domain (IPR014044)
- CAP-associated domain (IPR029410)
- Pathogenesis-related protein 1-like, SCP domain (IPR034111)
- Golgi-associated plant pathogenesis-related protein 1, SCP domain (IPR034113)
- Cysteine-rich secretory protein, SCP domain (IPR034117)
- Pry1-like, SCP domain (IPR034120)
- Glioma pathogenesis-related protein 1-like, SCP domain (IPR034121)
- Peptidase inhibitor 16-like, SCP domain (IPR034124)
- Venom allergen 3, insect (IPR034763)
The cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins (CAP) superfamily proteins are found in a wide range of organisms, including prokaryotes [PMID: 12625841] and non-vertebrate eukaryotes [PMID: 12759345], The nine subfamilies of the mammalian CAP superfamily include: the human glioma pathogenesis-related 1 (GLIPR1), Golgi associated pathogenesis related-1 (GAPR1) proteins, peptidase inhibitor 15 (PI15), peptidase inhibitor 16 (PI16), cysteine-rich secretory proteins (CRISPs), CRISP LCCL domain containing 1 (CRISPLD1), CRISP LCCL domain containing 2 (CRISPLD2), mannose receptor like and the R3H domain containing like proteins. Members are most often secreted and have an extracellular endocrine or paracrine function and are involved in processes including the regulation of extracellular matrix and branching morphogenesis, potentially as either proteases or protease inhibitors; in ion channel regulation in fertility; as tumour suppressor or pro-oncogenic genes in tissues including the prostate; and in cell-cell adhesion during fertilisation. The overall protein structural conservation within the CAP superfamily results in fundamentally similar functions for the CAP domain in all members, yet the diversity outside of this core region dramatically alters the target specificity and, thus, the biological consequences [PMID: 18824526]. The Ca++-chelating function [PMID: 12759345] would fit with the various signalling processes (e.g. the CRISP proteins) that members of this family are involved in, and also the sequence and structural evidence of a conserved pocket containing two histidines and a glutamate. It also may explain how Q91055 blocks the Ca++ transporting ryanodine receptors.
The CAP domain forms a unique 3 layer alpha-beta-alpha fold with some, though not all, of the structural elements found in proteases [PMID: 18824526].