Rothwell V, Kosowski S, Hadjilambris O, Baska R, Norman J
Bristol-Myers Squibb, Seattle, WA 98121.
DNA Cell Biol. 1993 May;12(4):291-8. doi: 10.1089/dna.1993.12.291.
Renin is a mammalian aspartic protease that is rate-limiting in the renin-angiotensin cascade. Preprorenin is the translational product of the human renin gene and is secreted as prorenin, an inactive zymogen, primarily from the juxtaglomerular cells of the kidney. It has previously been shown that the 46-amino-acid pro domain is not necessary for the secretion of fully active or mature renin from mammalian cells. Additionally, previous reports indicated that glycosylation of Asn-5 and Asn-75, the two potential sites of N-glycosylation in renin, is not necessary for the secretion of prorenin from mammalian cells. In the present study, the role of N-glycosylation in the secretion of mature renin was examined. Asn to Ser mutations at one or both of the glycosylation sites of mature renin were made and the expression of these constructs was examined in COS, CHO, and Sf9 insect cells. In the absence of the pro sequence, N-glycoylation at Asn-75 was essential for the secretion of active renin protein from all three cell types. The mutation at Asn-75 caused a more dramatic reduction in renin secretion than the mutation at Asn-5. This is in contrast to results previously reported for prorenin.
肾素是一种哺乳动物天冬氨酸蛋白酶，在肾素-血管紧张素级联反应中起限速作用。前肾素原是人类肾素基因的翻译产物，主要作为无活性的酶原——肾素原从肾脏的球旁细胞分泌。此前已经表明，46个氨基酸的前结构域对于从哺乳动物细胞分泌完全活性或成熟的肾素并非必需。此外，先前的报道指出，肾素中两个潜在的N-糖基化位点Asn-5和Asn-75的糖基化对于从哺乳动物细胞分泌肾素原并非必需。在本研究中，研究了N-糖基化在成熟肾素分泌中的作用。对成熟肾素的一个或两个糖基化位点进行了Asn到Ser的突变，并在COS、CHO和Sf9昆虫细胞中检测了这些构建体的表达。在没有前序列的情况下，Asn-75处的N-糖基化对于从所有三种细胞类型分泌活性肾素蛋白至关重要。Asn-75处的突变比Asn-5处的突变导致肾素分泌的减少更为显著。这与先前报道的肾素原的结果相反。
