UMA and MABP domains throw light on receptor endocytosis and selection of endosomal cargoes

Abstract

Interactions of the ESCRT complexes are critical for endosomal trafficking. We identify two domains with potential significance for this process. The MABP domain present in metazoan ESCRT-I/MVB12 subunits, Crag, a regulator of protein sorting, and bacterial pore-forming proteins might mediate novel membrane interactions in trafficking. The UBAP1-MVB12-associated UMA domain found in MVB12 and UBAP1 defines a novel adaptor that might recruit diverse targets to ESCRT-I.

Supplementary information: Supplementary data are available at ftp://ftp.ncbi.nih.gov/pub/aravind/UMA/MVB12.html.

Fig. 1.

Multiple sequence alignment of the UMA (A) and MAPB (B) domains. Residues are colored according to the 85% consensus. Conserved MAPB positions are highlighted as listed in the lower box.

Fig. 2.

(A) Domain architectures of UMA and MAPB containing proteins. (B) Structure of the MAPB domain from P.luminescens plu1415 (PDB: 2QP2). Conserved residues P and Y of the second strand's signature (PXGY, see Fig. 1) are represented as spheres. Only known domains are represented above, with unknown or uncharacterized regions omitted for simplicity. See text for domain name abbreviations.