|Human, Monkey, Mouse, Rat|
Application Methods: Immunoprecipitation, Western Blotting
Background: Class II phosphatidylinositol 3-kinases (PI3K) contain a C-terminal C2 domain that is unique to the class II isoforms of the PI3K family. This C2 domain mediates protein and phospholipid binding acitivities (1,2). PI3K Class II α generates phosphatidylinositol 3-phosphate (PIP3) and phosphatidylinositol 3,4-bisphosphate (PI(3, 4)P2) from phosphatidylinositol and phosphatidylinositol 4-phosphate (3). PI3K Class II α is located in various intracellular locations such as the trans-Golgi network, endocytic compartments, clathrin-coated vesicles, and nuclear speckles (1,4,5). Research studies have indicated that PI3K Class II α regulates the assembly and distribution of clathrin, resulting in the modulation of clathrin-dependent trafficking and sorting within the trans Golgi network (5,6). PI3K Class II α also mediates translocation of the glucose transporter GLUT4 to the plasma membrane in response to insulin (7). PI3K Class II α has also been shown to regulate neurosecretory granule exocytosis (8) and vascular smooth muscle contraction (9). Unlike other PI3K family members, PI3K Class II α is less sensitive to the PI3K inhibitors wortmannin and LY294002 (3).
|Human, Monkey, Mouse, Rat|
Application Methods: Immunofluorescence (Immunocytochemistry), Immunoprecipitation, Western Blotting
Background: Eps15 (EGFR pathway substrate 15) was originally discovered as a substrate for the kinase activity of EGFR (1). Eps15 has a tripartite structure comprising an amino terminal portion, which contains three evolutionarily conserved EH protein-protein interaction domains, a central putative coiled-coil region required for constitutive oligmerization, and a carboxy terminal domain containing multiple copies of the amino acid triplet Asp-Pro-Phe that constitute the AP2 binding domain. The carboxy terminal domain also contains two ubiquitin interaction motifs (UIMs), the last of which is indespensible for Eps15 binding to ubiquitin (1). Several lines of evidence support a role for Eps15 in clathrin-mediated endocytosis, including the endocytosis of synaptic vesicles. Eps15 binds to AP2 as well as other proteins involved in endocytosis and/or synaptic vesicle recycling, such as synaptojanin1 and epsin. Furthermore, Eps15 colocalizes with markers of the plasma membrane clathrin-coated pits and vesicles (2). Eps15 regulates the endosomal trafficking of c-Met (3) and EGFR (4), possibly by recruiting the ubiquitinated receptors to the rims of clathrin-coated pits through interaction between the ubiquitin tag and its UIMs.The EPS15 gene yields two isoforms that are believed to reside in distinct subcellular locations and are thus implicated in different facets of endosomal trafficking (5). Human EPS15 has been mapped to chromosome 1p31-p32, a region displaying several nonrandom chromosomal abnormalities, including deletions in neuroblastoma and translocations in acute lymphoblastic and myeloid leukemias. Research has shown two translocations t(1;11)(p32;q11) are found in rare cases of myeloid leukemia where the Eps15 gene was fused to the HRX gene, resulting in two reciprocal fusion genes (6).