Yamaguchi N, Fukuda M N
La Jolla Cancer Research Foundation, California 92037, USA.
J Biol Chem. 1995 May 19;270(20):12170-6. doi: 10.1074/jbc.270.20.12170.
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.
最近对存在于高尔基体复合物中的蛋白质的研究表明，这些蛋白质的跨膜结构域在很大程度上决定了它们在高尔基体复合物中的滞留。我们在此表明，β-1,4-半乳糖基转移酶（GT）在体内形成同型二聚体和大的寡聚体，并且同型二聚体的形成依赖于跨膜结构域内的半胱氨酸和组氨酸残基。这些残基的双重突变，即Cys29→Ser和His32→Leu，消除了同型二聚化并同时降低了高尔基体滞留。用抗GT和抗报告分子抗体对GT和各种GT嵌合体进行共免疫沉淀显示，GT的大聚集体与α-和β-微管蛋白以及其他细胞蛋白相关联。微管蛋白与GT之间的这种关联表明细胞骨架在高尔基体滞留机制中起支持作用。
