Tail-specific antibodies that block return of 46,000 M(r) mannose 6-phosphate receptor to the trans-Golgi network.
Recycling of 46,000 M(r) mannose 6-phosphate receptor (MPR 46) was investigated by microinjection of Fab fragments against small epitopes within the cytoplasmic domain of the receptor. Fab fragments against the peptide 43-47 (Ala-Tyr-Arg-Gly-Val) efficiently blocked return of MPR 46 to the TGN. Antibody-induced redistribution resulted in accumulation of MPR 46 within an endosomal compartment, from which it recycled to the plasma membrane. Rab5 and rab7, markers for early and late endosomes, respectively, were not detectable in the compartment of redistributed MPR 46, suggesting that it represents a specialized endosomal subcompartment. The bulk of redistributed MPR 46 did not colocalize with endocytosed fluid-phase marker, suggesting that it accumulates at a site where MPR 46 has been segregated from endocytosed material, which is destined for transport to lysosomes. Peptide 43-47 contains a tyrosine (residue 44) which has been shown earlier to be part of an internalization signal for MPR 46 (Johnson, K. F., W. Chan, and S. Kornfeld. 1990. Proc. Natl. Acad. Sci. USA. 87:10010-10014). The role of tyrosine residue 44 as part of a putative multifunctional sorting signal is discussed.
Schulze-Garg
C
C
Universität Göttingen, Federal Republic of Germany.
Böker
C
C
Nadimpalli
S K
SK
von Figura
K
K
Hille-Rehfeld
A
A
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology*; D002460:Cell Line; D002478:Cells, Cultured; D006224:Cricetinae; D004705:Endocytosis; D000939:Epitopes; D006056:Golgi Apparatus / Q000378:metabolism*; D006801:Humans; D007140:Immunoglobulin Fab Fragments; D007425:Intracellular Membranes / Q000378:metabolism; D008845:Microinjections; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009842:Oligopeptides / Q000276:immunology; D015388:Organelles / Q000378:metabolism; D017527:Receptor, IGF Type 2 / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*
D000906:Antibodies; D000939:Epitopes; D007140:Immunoglobulin Fab Fragments; D009842:Oligopeptides; D017527:Receptor, IGF Type 2