Maintain refrigerated at 2-8°C for up to 6 months. For long term storage store at -20°C in small aliquots to prevent freeze-thaw cycles.

Clathrin-coated vesicles, involved in endocytosis and Golgi processing, have a surface lattice containing clathrin triskelia and stoichiometric amounts of additional components termed assembly proteins, or APs. The AP form at the plasma membrane, AP2, is composed of two large subunits of 100-115 kDa, denoted AP2 alpha and AP2 beta, a medium chain of 50 kDa, designated AP50, and a small chain (1). The medium chain AP2 mu1 interacts specifically with the tyrosine-based signals of several integral membrane proteins through the consensus sequence YXXPhi, where X can be any residue and Phi is a large hydrophobic residue (2). Phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P(2)] is an important factor for a variety of cellular functions ranging from cell signaling to actin cytoskeletal dynamics and endocytic membrane traffic. It has been shown that the clathrin adaptor complex AP2 is a regulator of phosphatidylinositol 4-phosphate 5-kinase (PIPK)-mediated PI(4,5)P(2) synthesis. AP2 directly interacts with the kinase core domain of type I PIPK isozymes via its mu2-subunit in vitro and in native protein extracts (3).

A synthetic peptide corresponding to residues near the C-terminus of human AP2 mu1 was used as an immunogen.

Rabbit

50 mM Tris-Glycine (pH 7.4), 0.15 M NaCl, 40% Glycerol, 0.01% sodium azide and 0.05% BSA.

1. Druck T, et al. Genomics 30(1):94-7, 1995<br>2. Follows ER, et al. Biochem J 359(2):427-34, 2001<br>3. Proc Natl Acad Sci 103(32):11934-9, 2006<br>

Human, Mouse, Rat

AP-2 complex subunit mu, AP-2 mu chain, Adaptin-mu2, Adaptor protein complex AP-2 subunit mu, Adaptor-related protein complex 2 subunit mu, Clathrin assembly protein complex 2 mu medium chain, Clathrin coat assembly protein AP50, Clathrin coat-associated protein AP50, HA2 50 kDa subunit, Plasma membrane adaptor AP-2 50 kDa protein, AP2M1, CLAPM1, KIAA0109

WB~~1:5000~50000

Function Component of the adaptor protein complex 2 (AP-2). Adaptor protein complexes function in protein transport via transport vesicles in different membrane traffic pathways. Adaptor protein complexes are vesicle coat components and appear to be involved in cargo selection and vesicle formation. AP-2 is involved in clathrin-dependent endocytosis in which cargo proteins are incorporated into vesicles surrounded by clathrin (clathrin- coated vesicles, CCVs) which are destined for fusion with the early endosome. The clathrin lattice serves as a mechanical scaffold but is itself unable to bind directly to membrane components. Clathrin-associated adaptor protein (AP) complexes which can bind directly to both the clathrin lattice and to the lipid and protein components of membranes are considered to be the major clathrin adaptors contributing the CCV formation. AP-2 also serves as a cargo receptor to selectively sort the membrane proteins involved in receptor-mediated endocytosis. AP-2 seems to play a role in the recycling of synaptic vesicle membranes from the presynaptic surface. AP-2 recognizes Y-X-X-[FILMV] (Y-X-X-Phi) and [ED]-X-X-X-L-[LI] endocytosis signal motifs within the cytosolic tails of transmembrane cargo molecules. AP-2 may also play a role in maintaining normal post-endocytic trafficking through the ARF6-regulated, non-clathrin pathway. The AP-2 mu subunit binds to transmembrane cargo proteins; it recognizes the Y-X-X-Phi motifs. The surface region interacting with to the Y-X- X-Phi motif is inaccessible in cytosolic AP-2, but becomes accessible through a conformational change following phosphorylation of AP-2 mu subunit at 'Tyr-156' in membrane- associated AP-2. The membrane-specific phosphorylation event appears to involve assembled clathrin which activates the AP-2 mu kinase AAK1 (By similarity). Plays a role in endocytosis of frizzled family members upon Wnt signaling (By similarity). Cellular_Location Cell membrane. Membrane, coated pit; Peripheral membrane protein; Cytoplasmic side. Note=AP-2 appears to be excluded from internalizing CCVs and to disengage from sites of endocytosis seconds before internalization of the nascent CCV