Seabra M C, Brown M S, Goldstein J L
Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.
Science. 1993 Jan 15;259(5093):377-81. doi: 10.1126/science.8380507.
Rab geranylgeranyl transferase (GG transferase) is a two-component enzyme that attaches 20-carbon isoprenoid groups to cysteine residues in Rab proteins, a family of guanosine triphosphate-binding proteins that regulate vesicular traffic. The mutant gene in human choroideremia, an X-linked form of retinal degeneration, encodes a protein that resembles component A of rat Rab GG transferase. Lymphoblasts from choroideremia subjects showed a marked deficiency in the activity of component A, but not component B, of Rab GG transferase. The deficiency was more pronounced when the substrate was Rab3A, a synaptic vesicle protein, than it was when the substrate was Rab1A, a protein of the endoplasmic reticulum. The data imply the existence of multiple component A proteins, one of which is missing in choroideremia.
Rab geranylgeranyl转移酶（GG转移酶）是一种双组分酶，可将20碳异戊二烯基团连接到Rab蛋白的半胱氨酸残基上，Rab蛋白是一类调节囊泡运输的鸟苷三磷酸结合蛋白。人类脉络膜视网膜病变（一种X连锁形式的视网膜变性）中的突变基因编码一种类似于大鼠Rab GG转移酶A组分的蛋白质。脉络膜视网膜病变患者的淋巴母细胞显示Rab GG转移酶的A组分活性明显缺乏，但B组分活性正常。当底物是突触囊泡蛋白Rab3A时，这种缺乏比底物是内质网蛋白Rab1A时更为明显。这些数据表明存在多种A组分蛋白，其中一种在脉络膜视网膜病变中缺失。
