InterPro domain: IPR000270

The PB1 (Phox and Bem1) domain, comprising about 80 amino acid residues, isconserved among animals, fungi, amoebas, and plants. It functions as a proteinbinding module through PB1-mediated heterodimerization or homo-oligomerization[ 1 , 2 , 3 , 4 ].

The PB1 domains adopt an ubiquitin-like beta-grasp fold, containing two alphahelices and a mixed five-stranded beta sheet. The beta-sheethas a convex surface, and alpha1 fits into the cavity formed by the sheet. PB1domains may display an acidic surface (type I), a basic surface (tape II), orboth surfaces (type I/II) on opposite faces of the domain structure to allowfor front-to-back orientation of multiple PB1 domains [ 5 , 5 , 5 , 5 , 5 ].

1. Structure and function of the PB1 domain, a protein interaction module conserved in animals, fungi, amoebas, and plants. Sci. STKE 2007, re6
2. Structure of a cell polarity regulator, a complex between atypical PKC and Par6 PB1 domains. J. Biol. Chem. 280, 9653-61
3. Structure and ligand recognition of the PB1 domain: a novel protein module binding to the PC motif. EMBO J. 20, 3947-56
4. Molecular basis for AUXIN RESPONSE FACTOR protein interaction and the control of auxin response repression. Proc. Natl. Acad. Sci. U.S.A. 111, 5427-32
5. Structural basis for oligomerization of auxin transcriptional regulators. Nat Commun 5, 3617