title: Mechanism for amyloid precursor-like protein 2 enhancement of major histocompatibility complex class I molecule degradation.
abstract: Earlier studies have demonstrated interaction of the murine major histocompatibility complex (MHC) class I molecule K(d) with amyloid precursor-like protein 2 (APLP2), a ubiquitously expressed member of the amyloid precursor protein family. Our current findings indicate that APLP2 is internalized in a clathrin-dependent manner, as shown by utilization of inhibitors of the clathrin pathway. Furthermore, we demonstrated that APLP2 and K(d) bind at the cell surface and are internalized together. The APLP2 cytoplasmic tail contains two overlapping consensus motifs for binding to the adaptor protein-2 complex, and mutation of a tyrosine shared by both motifs severely impaired APLP2 internalization and ability to promote K(d) endocytosis. Upon increased expression of wild type APLP2, K(d) molecules were predominantly directed to the lysosomes rather than recycled to the plasma membrane. These findings suggest a model in which APLP2 binds K(d) at the plasma membrane, facilitates uptake of K(d) in a clathrin-dependent manner, and routes the endocytosed K(d) to the lysosomal degradation pathway. Thus, APLP2 has a multistep trafficking function that influences the expression of major histocompatibility complex class I molecules at the plasma membrane.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA.
authors.forename: Amit
authors.initials: A
authors.lastname: Tuli
authors.forename: Mahak
authors.initials: M
authors.lastname: Sharma
authors.forename: Haley L
authors.initials: HL
authors.lastname: Capek
authors.forename: Naava
authors.initials: N
authors.lastname: Naslavsky
authors.forename: Steve
authors.initials: S
authors.lastname: Caplan
authors.forename: Joyce C
authors.initials: JC
authors.lastname: Solheim
mesh_terms: D020816:Amino Acid Motifs; D016564:Amyloid beta-Protein Precursor / Q000737:chemistry / Q000378:metabolism*; D000911:Antibodies, Monoclonal / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D034281:Dynamins / Q000737:chemistry; D004705:Endocytosis; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D008285:Major Histocompatibility Complex; D008954:Models, Biological; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D015398:Signal Transduction
chemical_list: C084104:APLP2 protein, human; D016564:Amyloid beta-Protein Precursor; D000911:Antibodies, Monoclonal; D009419:Nerve Tissue Proteins; D049452:Green Fluorescent Proteins; D034281:Dynamins