AP4S1

Description

The AP4S1 (adaptor related protein complex 4 subunit sigma 1) is a protein-coding gene located on chromosome 14.

AP-4 complex subunit sigma-1 is a protein encoded by the AP4S1 gene in humans. AP-4 is a heterotetrameric adaptor protein complex involved in sorting integral membrane proteins during the endocytic and secretory pathways. It consists of two large chains, beta-4 (AP4B1) and epsilon-4 (AP4E1), a medium chain, mu-4 (AP4M1), and a small chain, sigma-4 (AP4S1). AP-4 deficiency causes childhood-onset hereditary spastic paraplegia, suggesting its crucial role in brain development and function.

AP-4 is a protein complex involved in vesicle formation and cargo selection, playing a crucial role in vesicular transport of proteins in various trafficking pathways. It forms a non-clathrin coat on vesicles originating from the trans-Golgi network (TGN) and potentially directs proteins from the TGN to the endosomal-lysosomal system. AP-4 also participates in protein sorting to the basolateral membrane in epithelial cells and the proper localization of somatodendritic proteins in neurons. It recognizes and binds tyrosine-based sorting signals on cargo proteins, but may also interact with other sorting signals.

AP4S1 is also known as AP47B, CLA20, CLAPS4, CPSQ6, SPG52.

Associated Diseases

• Severe intellectual disability and progressive spastic paraplegia
• Spastic paraplegia 52, autosomal recessive