Davis C A, Riddell D C, Higgins M J, Holden J J, White B N
Nucleic Acids Res. 1985 Sep 25;13(18):6605-19. doi: 10.1093/nar/13.18.6605.
We have isolated a clustered gene family in D. melanogaster that codes for trypsin-like enzymes. The gene family has been localized to 47D-F by in situ hybridization to polytene chromosomes. The four genes in the family are transcribed in alternating orientations, and code for 1000 nt mRNAs. Transcripts are present at all stages of the life cycle. In situ hybridization to mRNA in tissue sections of third instar larvae showed that transcripts were restricted to the mid-gut. One gene was sequenced. The translated amino acid sequence of the proposed active enzyme is 42% homologous to bovine trypsin. Regions of functional importance are more strongly conserved. These include the active site residues asp102, his57, ser195, and the residue asp189 which is reputed to bind the basic residue at the substrate cleavage site. The activation peptide is not homologous to that of most vertebrate trypsins, suggesting a modified activation mechanism. The sequence further strengthens the hypothesis that the chymotrypsin cleavage specificity developed separately in the vertebrates and invertebrates.
我们在黑腹果蝇中分离出了一个成簇的基因家族，该家族编码类胰蛋白酶。通过对多线染色体进行原位杂交，该基因家族已被定位到47D-F区域。家族中的四个基因以交替的方向转录，编码1000个核苷酸的mRNA。转录本在生命周期的所有阶段都存在。对三龄幼虫组织切片中的mRNA进行原位杂交显示，转录本局限于中肠。对其中一个基因进行了测序。推测的活性酶的翻译氨基酸序列与牛胰蛋白酶有42%的同源性。功能重要区域的保守性更强。这些区域包括活性位点残基asp102、his57、ser195，以及据信在底物切割位点结合碱性残基的asp189残基。激活肽与大多数脊椎动物胰蛋白酶的激活肽不同源，这表明激活机制有所改变。该序列进一步强化了这样一种假说，即胰凝乳蛋白酶的切割特异性在脊椎动物和无脊椎动物中是分别发展而来的。
