Adaptor Related Protein Complex 1 Sigma 1 (AP1s1)

AP-1 complex subunit sigma-1A is part of the clathrin coat assembly complex which links clathrin to receptors in coated vesicles. These vesicles are involved in endocytosis and Golgi processing. This protein, as well as beta-prime-adaptin, gamma-adaptin, and the medium (mu) chain AP47, form the AP-1 assembly protein complex located at the Golgi vesicle. Two alternatively spliced transcript variants of this gene, which encode distinct isoforms, have been reported.The predicted rat AP17 shares 45% protein sequence identity with mouse AP19. Takatsu et al. (1998) identified a human cDNA encoding AP19, which they designated sigma-1A. They reported that the predicted mouse and human AP19 proteins are identical. Northern blot analysis revealed that the approximately 1.4-kb AP19 mRNA was expressed ubiquitously in human tissues.