Alternative titles; symbols
HGNC Approved Gene Symbol: AP2A1
Cytogenetic location: 19q13.33 Genomic coordinates (GRCh38): 19:49,767,001-49,807,114 (from NCBI)
Two separate AP2-alpha adaptor subunits of the clathrin coat assembly complex of the mouse were cloned by Robinson (1989). The alpha subunit is part of the so-called AP2 coat assembly protein complex (see 601024) which links clathrin (118960) to receptors in the coated vesicles. The alpha adaptins are exclusively found in the endocytic coated vesicles. The 2 mouse proteins are 84% identical.
Huntingtin-interacting protein 1 (HIP1; 601767) is enriched in membrane-containing cell fractions and has been implicated in vesicle trafficking. It is a multidomain protein containing an epsin (607262) N-terminal homology (ENTH) domain, a central coiled-coil-forming region, and a C-terminal actin-binding domain. Waelter et al. (2001) identified 3 HIP1-associated proteins, clathrin heavy chain (CLTC; 118955) and alpha-adaptin A and C. In vitro binding studies revealed that the central coiled-coil domain of HIP1 is required for the interaction with clathrin, whereas DPF-like motifs located upstream to this domain are important for HIP1 binding to the C-terminal 'appendage' domain of alpha-adaptin A and C. Expression of full-length HIP1 in mammalian cells resulted in a punctate cytoplasmic immunostaining characteristic of clathrin-coated vesicles. The authors hypothesized that HIP1 is an endocytic protein, the structural integrity of which may be crucial for maintenance of normal vesicle size in vivo.
Robinson, M. S. Cloning of cDNAs encoding two related 100-kD coated vesicle proteins (alpha-adaptins). J. Cell Biol. 108: 833-42, 1989. [PubMed: 2564002] [Full Text: https://doi.org/10.1083/jcb.108.3.833]
Waelter, S., Scherzinger, E., Hasenbank, R., Nordhoff, E., Lurz, R., Goehler, H., Gauss, C., Sathasivam, K., Bates, G. P., Lehrach, H., Wanker, E. E. The huntingtin interacting protein HIP1 is a clathrin and alpha-adaptin-binding protein involved in receptor-mediated endocytosis. Hum. Molec. Genet. 10: 1807-1817, 2001. [PubMed: 11532990] [Full Text: https://doi.org/10.1093/hmg/10.17.1807]