Fleischer B, McIntyre J O, Kempner E S
Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235.
Biochemistry. 1993 Mar 2;32(8):2076-81. doi: 10.1021/bi00059a027.
Target inactivation analysis was used to measure the functional size of uridine diphosphogalactose: N-acetylglucosamine beta(1,4)galactosyltransferase (galactosyltransferase), cytidine monophospho-N-acetyl-neuraminic acid: beta-galactoside alpha(2,6) sialytransferase (sialyltransferase), and uridine diphosphatase (UDPase) in Golgi membranes isolated from rat liver. The size of nucleoside diphosphatase (NDPase), an enzyme similar to UDPase but localized in rat liver endoplasmic reticulum, was also estimated by target inactivation analysis. The related enzymes, UDPase and NDPase, have target sizes of 96 +/- 4 and 77 +/- 3 kDa, while galactosyltransferase and sialyltransferase have target sizes of 97 +/- 10 and 130 +/- 20 kDa, respectively. The target inactivation sizes of galactosyltransferase and of sialyltransferase are about twice the monomer molecular weights of these enzymes obtained from sedimentation studies of the solubilized membranes as well as those predicted from previously reported cDNA sequences. We conclude from our studies that galactosyltransferase and sialyltransferase probably function as dimers in the Golgi membrane.
N-乙酰葡糖胺β(1,4)半乳糖基转移酶（半乳糖基转移酶）、胞苷单磷酸-N-乙酰神经氨酸：β-半乳糖苷α(2,6)唾液酸转移酶（唾液酸转移酶）和尿苷二磷酸酶（UDP酶）的功能大小。还通过靶失活分析法估算了核苷二磷酸酶（NDP酶）的大小，该酶与UDP酶相似，但定位于大鼠肝脏内质网。相关酶UDP酶和NDP酶的靶大小分别为96±4 kDa和77±3 kDa，而半乳糖基转移酶和唾液酸转移酶的靶大小分别为97±10 kDa和130±20 kDa。半乳糖基转移酶和唾液酸转移酶的靶失活大小约为通过对溶解膜的沉降研究获得的这些酶的单体分子量的两倍，也是根据先前报道的cDNA序列预测的分子量的两倍。我们从研究中得出结论，半乳糖基转移酶和唾液酸转移酶可能在高尔基体膜中以二聚体形式发挥作用。
