| Type: | Domain | Name: | Major sperm protein (MSP) domain |
| Description: | Nematode sperm are unusual amoeboid cells in which motility is not based on actin, but instead on the major sperm protein (MSP). MSP is a dimeric molecule that polymerises to form non-polar filaments constructed from two helical subfilaments that wind round one another. The filaments then assemble into larger macromolecular assemblies called fibre complexes. MSP is a small (~14 kDa) basic protein typically encoded by a multigene family of up to 28 members [, , , ]. An about 120-amino acid domain similar to MSP has been found in other proteins, including:Animal Vesicle-Associated Membrane Protein-associated (VAMP-associated) protein family of 33 kDa (VAP33). VAP33 is required for neurotransmitterrelease. It binds to the v-SNARE synaptobrevin/VAMP which is associated with vesicle fusion. VAP33 has a two-domain structure with its N terminusbeing highly homologous to MSP, whereas its C terminus is based on a putative alpha-helical coiled-coil combined with an extremly hydrophobicmembrane-attachment region [].Nicotiana plumbaginifolia VAP27, a VAP33 homologue. It interacts with the resistance protein Cf9 [].Yeast inositol regulator SCS2, a VAP33 homologue. It is C-terminally anchored to the endoplasmic reticulum [].The MSP polypeptide chain has an immunoglobulin-like fold based on a seven- stranded beta sandwich measuring approximately 15 A x 20 A x 45 A and havingopposing three-stranded and four-stranded beta sheets [].This entry represents the MSP domain. | Short Name: | MSP_dom |
