Kao W Y, Case S T
J Cell Biol. 1985 Sep;101(3):1044-51. doi: 10.1083/jcb.101.3.1044.
Chironomus salivary glands contain a family of high Mr (approximately 1,000 X 10(3)) secretion polypeptides thought to consist of three components: sp-Ia, sp-Ib, and sp-Ic. The use of a new extraction protocol revealed a novel high Mr component, sp-Id. Results of a survey of individual salivary glands indicated that sp-Id was widespread in more than a dozen strains of C. tentans and C. pallidivittatus. Sp-Id was phosphorylated at Ser residues, and a comparison of cyanogen bromide and tryptic peptide maps of 32P-labeled polypeptides suggested that sp-Ia, sp-Ib, and sp-Id are comprised of similar but nonidentical tandemly repeated amino acid sequences. We concluded that sp-Id is encoded by an mRNA whose size and nucleotide sequence organization are similar to Balbiani ring (BR) mRNAs that code for the other sp-I components. Furthermore, parallel repression of sp-Ib and sp-Id synthesis by galactose led us to hypothesize that both of their genes exist within Balbiani ring 2.
摇蚊唾液腺含有一族高分子量(约1000×10³)的分泌多肽,被认为由三个组分组成:sp-Ia、sp-Ib和sp-Ic。一种新提取方案的应用揭示了一种新的高分子量组分,sp-Id。对单个唾液腺的调查结果表明,sp-Id广泛存在于十几种细摇蚊和苍白摇蚊品系中。Sp-Id在丝氨酸残基处被磷酸化,对32P标记多肽的溴化氰和胰蛋白酶肽图的比较表明,sp-Ia、sp-Ib和sp-Id由相似但不相同的串联重复氨基酸序列组成。我们得出结论,sp-Id由一种mRNA编码,其大小和核苷酸序列组织与编码其他sp-I组分的巴尔比亚尼环(BR)mRNA相似。此外,半乳糖对sp-Ib和sp-Id合成的平行抑制使我们推测它们的基因都存在于巴尔比亚尼环2内。