title: Golgi retention mechanism of beta-1,4-galactosyltransferase. Membrane-spanning domain-dependent homodimerization and association with alpha- and beta-tubulins.
abstract: Recent studies on proteins residing in the Golgi complex revealed that the membrane-spanning domain of these proteins are largely responsible for their retention in the Golgi complex. We show here that beta-1,4-galactosyltransferase (GT) forms homodimers and large oligomers in vivo, and the formation of the homodimers is dependent on cysteine and histidine residues within the transmembrane domain. Double mutations of these residues, Cys29-->Ser and His32-->Leu, abolish homodimerization and simultaneously reduce the Golgi retention. Co-immunoprecipitation of GT and various GT chimeras with anti-GT and anti-reporter molecule antibodies revealed that large aggregates of GT are associated with alpha- and beta-tubulins and also with other cellular proteins. This association between tubulins and GT suggests a supportive role of the cytoskeleton in the Golgi retention mechanism.
authors.affiliation: La Jolla Cancer Research Foundation, California 92037, USA.
authors.forename: N
authors.initials: N
authors.lastname: Yamaguchi
authors.forename: M N
authors.initials: MN
authors.lastname: Fukuda
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002461:Cell Line, Transformed; D002522:Chlorocebus aethiops; D003545:Cysteine / Q000737:chemistry; D006056:Golgi Apparatus / Q000378:metabolism*; D006639:Histidine / Q000737:chemistry; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009237:N-Acetyllactosamine Synthase / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D014404:Tubulin / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D014404:Tubulin; D006639:Histidine; D009237:N-Acetyllactosamine Synthase; D003545:Cysteine