Capraro M A, Hughey R P
FEBS Lett. 1983 Jun 27;157(1):139-43. doi: 10.1016/0014-5793(83)81132-6.
The biosynthesis of rat renal gamma-glutamyltranspeptidase (EC 2.3.2.2) was studied by sodium dodecyl sulfate gel electrophoresis and fluorography of specific immunoprecipitates obtained at varying times' postinjection with [35S]methionine. At 20 min postinjection 3 endo-beta-N-acetylglucosaminidase H-sensitive bands were observed representing the propeptide (Mr 75 000) large subunit (Mr 49 500) and small subunit (Mr 29 000) of transpeptidase. The alterations in Mr are consistent with removal of 6 N-linked coreoligosaccharides from the propeptide; 4 from the large subunit and 2 from the small subunit. All 3 bands became more diffuse and less endoglycosidase H-sensitive by 40 min and completely resistant by 60 min postinjection. At 20 h postinjection no propeptide remained. Thus, the primary propeptide cleavage reaction occurs prior to the loss of endoglycosidase H sensitivity while about 30% of the propeptide is processed along with the heterodimer and cleaved at a later time.
通过十二烷基硫酸钠凝胶电泳和对注射[35S]甲硫氨酸后不同时间获得的特异性免疫沉淀物进行荧光自显影，研究了大鼠肾γ-谷氨酰转肽酶（EC 2.3.2.2）的生物合成。注射后20分钟，观察到3条对内切β-N-乙酰葡糖胺糖苷酶H敏感的条带，分别代表转肽酶的前肽（Mr 75 000）、大亚基（Mr 49 500）和小亚基（Mr 29 000）。Mr的变化与从前肽中去除6个N-连接的核心寡糖一致；大亚基去除4个，小亚基去除2个。注射后40分钟时，所有3条条带变得更加弥散，对内切糖苷酶H的敏感性降低，注射后60分钟时完全不敏感。注射后20小时，不再有前肽残留。因此，初级前肽切割反应发生在内切糖苷酶H敏感性丧失之前，而约30%的前肽与异二聚体一起加工，并在稍后时间被切割。
