PB1 domain
SMART accession number:SM00666
Description: Phox and Bem1p domain, present in many eukaryotic cytoplasmic signalling proteins. The domain adopts a beta-grasp fold, similar to that found in ubiquitin and Ras-binding domains. A motif, variously termed OPR, PC and AID, represents the most conserved region of the majority of PB1 domains, and is necessary for PB1 domain function. This function is the formation of PB1 domain heterodimers, although not all PB1 domain pairs associate.
Interpro abstract (IPR000270):

The PB1 (Phox and Bem1) domain, comprising about 80 amino acid residues, is conserved among animals, fungi, amoebas, and plants. It functions as a protein binding module through PB1-mediated heterodimerization or homo-oligomerization [(PUBMED:17726178), (PUBMED:15590654), (PUBMED:11483498), (PUBMED:24706860)].

The PB1 domains adopt an ubiquitin-like beta-grasp fold, containing two alpha helices and a mixed five-stranded beta sheet. The beta-sheet has a convex surface, and alpha1 fits into the cavity formed by the sheet. PB1 domains may display an acidic surface (type I), a basic surface (tape II), or both surfaces (type I/II) on opposite faces of the domain structure to allow for front-to-back orientation of multiple PB1 domains [(PUBMED:17726178), (PUBMED:15590654), (PUBMED:11483498), (PUBMED:24706860)].

GO function:protein binding (GO:0005515)
Family alignment:
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There are 2943 PB1 domains in 2939 proteins in SMART's nrdb database.

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