AP4B1

The heterotetrameric adaptor protein (AP) complexes sort integral membrane proteins at various stages of the endocytic and secretory pathways. AP4 is composed of 2 large chains, beta-4 (AP4B1) and epsilon-4 (AP4E1; MIM 607244), a medium chain, mu-4 (AP4M1; MIM 602296), and a small chain, sigma-4 (AP4S1; MIM 607243).[supplied by OMIM

Full Name

adaptor-related protein complex 4, beta 1 subunit

Function

Component of the adaptor protein complex 4 (AP-4). Adaptor protein complexes are vesicle coat components involved both in vesicle formation and cargo selection. They control the vesicular transport of proteins in different trafficking pathways (PubMed:10066790, PubMed:10436028). AP-4 forms a non clathrin-associated coat on vesicles departing the trans-Golgi network (TGN) and may be involved in the targeting of proteins from the trans-Golgi network (TGN) to the endosomal-lysosomal system. It is also involved in protein sorting to the basolateral membrane in epithelial cells and the proper asymmetric localization of somatodendritic proteins in neurons. AP-4 is involved in the recognition and binding of tyrosine-based sorting signals found in the cytoplasmic part of cargos, but may also recognize other types of sorting signal (Probable).

Biological Process

Post-Golgi vesicle-mediated transport Source: Reactome
Protein localization Source: UniProtKB
Protein targeting Source: UniProtKB
Vesicle-mediated transport Source: GO_Central

Cellular Location

Trans-Golgi network membrane

Involvement in disease

Spastic paraplegia 47, autosomal recessive (SPG47): A form of spastic paraplegia, a neurodegenerative disorder characterized by a slow, gradual, progressive weakness and spasticity of the lower limbs. SPG47 is characterized by neonatal hypotonia that progresses to hypertonia and spasticity, and severe mental retardation with poor or absent speech development.