Interactions of the AP-1 Golgi adaptor with the polymeric immunoglobulin receptor and their possible role in mediating brefeldin A-sensitive basolateral targeting from the trans-Golgi network.
We provide morphological, biochemical, and functional evidence suggesting that the AP-1 clathrin adaptor complex of the trans-Golgi network interacts with the polymeric immunoglobulin receptor in transfected Madin-Darby canine kidney cells. Our results indicate that immunofluorescently labeled gamma-adaptin subunit of the adaptor complex and the polymeric immunoglobulin receptor partially co-localize in polarized and semi-polarized cells. gamma-Adaptin is co-immunoisolated with membranes expressing the wild-type receptor. The entire AP-1 adaptor complex could be chemically cross-linked to the receptor in filter-grown cells. gamma-Adaptin could be co-immunoprecipitated with the wild-type receptor, with reduced efficiency with receptor mutant whose basolateral sorting motif has been deleted, and not with receptor lacking its cytoplasmic tail. Co-immunoprecipitation of gamma-adaptin was inhibited by brefeldin A. Mutation of cytoplasmic serine 726 inhibited receptor interactions with AP-1 but did not abrogate the fidelity of its basolateral targeting from the trans-Golgi network. However, the kinetics of receptor delivery to the basolateral cell surface were slowed by the mutation. Although surface delivery of the wild-type receptor was inhibited by brefeldin A, the delivery of the mutant receptor was insensitive to the drug. Our results are consistent with a working model in which phosphorylated cytoplasmic serine modulates the recruitment of the polymeric immunoglobulin receptor into AP-1/clathrin-coated areas in the trans-Golgi network. This process may regulate the efficiency of receptor targeting from the trans-Golgi network.
Orzech
E
E
Department of Cell and Animal Biology, Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Schlessinger
K
K
Weiss
A
A
Okamoto
C T
CT
Aroeti
B
B
D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000818:Animals; D001485:Basement Membrane / Q000187:drug effects; D020126:Brefeldin A / Q000494:pharmacology*; D002460:Cell Line; D004285:Dogs; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D019056:Receptors, Polymeric Immunoglobulin / Q000235:genetics / Q000378:metabolism*
D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D008565:Membrane Proteins; D019056:Receptors, Polymeric Immunoglobulin; D020126:Brefeldin A