Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested materials. Endocytosis includes pinocytosis and phagocytosis. It is a form of active transport.
The AP2 adaptor complex is a multimeric protein that works on the cell membrane to internalize cargo in clathrin-mediated endocytosis. It is a stable complex of four adaptins which give rise to a structure that has a core domain and two appendage domains attached to the core domain by polypeptide linkers. These appendage domains are sometimes called 'ears'. The core domain binds to the membrane and to cargo destined for internalisation. The alpha and beta appendage domains bind to accessory proteins and to clathrin. Their interactions allow the temporal and spatial regulation of the assembly of clathrin-coated vesicles and their endocytosis.
Epidermal growth factor receptor substrate 15 is a protein that in humans is encoded by the EPS15 gene.
AP-2 complex subunit mu is a protein that in humans is encoded by the AP2M1 gene.
Disabled homolog 2 is a protein that in humans is encoded by the DAB2 gene.
AP-2 complex subunit alpha-1 is a protein that in humans is encoded by the AP2A1 gene.
AP-1 complex subunit mu-1 is a protein that in humans is encoded by the AP1M1 gene.
Clathrin heavy chain 1 is a protein that in humans is encoded by the CLTC gene.
AP-2 complex subunit alpha-2 is a protein that in humans is encoded by the AP2A2 gene.
AP-1 complex subunit beta-1 is a protein that in humans is encoded by the AP1B1 gene.
AP-2 complex subunit beta is a protein that in humans is encoded by the AP2B1 gene.
AP-1 complex subunit mu-2 is a protein that in humans is encoded by the AP1M2 gene.
AP-1 complex subunit sigma-1A is a protein that in humans is encoded by the AP1S1 gene.
Sorting nexin-9 is a protein that in humans is encoded by the SNX9 gene.
Epidermal growth factor receptor substrate 15-like 1 is a protein that in humans is encoded by the EPS15L1 gene.
Epsin-1 is a protein that in humans is encoded by the EPN1 gene.
AP-2 complex subunit sigma is a protein that in humans is encoded by the AP2S1 gene.
Clathrin adaptor proteins, also known as adaptins, are vesicular transport adaptor proteins associated with clathrin. These proteins are synthesized in the ribosomes, processed in the endoplasmic reticulum and transported from the Golgi apparatus to the trans-Golgi network, and from there via small carrier vesicles to their final destination compartment. The association between adaptins and clathrin are important for vesicular cargo selection and transporting. Clathrin coats contain both clathrin and adaptor complexes that link clathrin to receptors in coated vesicles. Clathrin-associated protein complexes are believed to interact with the cytoplasmic tails of membrane proteins, leading to their selection and concentration. Therefore, adaptor proteins are responsible for the recruitment of cargo molecules into a growing clathrin-coated pits. The two major types of clathrin adaptor complexes are the heterotetrameric vesicular transport adaptor proteins (AP1-5), and the monomeric GGA adaptors. Adaptins are distantly related to the other main type of vesicular transport proteins, the coatomer subunits, sharing between 16% and 26% of their amino acid sequence.
The C-terminal domain ofBeta2-adaptin is a protein domain is involved in cell trafficking by aiding import and export of substances in and out of the cell.
The arrestin family of proteins is subdivided into α-arrestins (also referred to as arrestin-related trafficking adaptors or arrestin-like yeast proteins in yeast or ARRDCs in mammals, β-arrestins and Vps26-like arrestins proteins. The α-Arrestins are an ancestral branch of the larger arrestin family of proteins and they are conserved across eukaryotes but are best characterized in the budding yeast Saccharomyces cerevisiae; to-date there are 6 α-arrestins identified in mammalian cells and 14 α-arrestins identified in the budding yeast Saccharomyces cerevisiae. The yeast α-arrestin family comprises Ldb19/Art1, Ecm21/Art2, Aly1/Art6, Aly2/Art3, Rod1/Art4, Rog3/Art7, Art5, Csr2/Art8, Rim8/Art9, Art10, Bul1, Bul2, Bul3 and Spo23. The best characterized α-arrestin function to date is their endocytic regulation of plasma membrane proteins, including G-protein coupled receptors and nutrient transporters. α-Arrestins control endocytosis of these membrane proteins in response to cellular stressors, including nutrient or metal ion excess.
