Viswanathan S, Dignam S S, Dignam J D
Department of Biochemistry, University of Mississippi Medical Center, Jackson 39216-4505.
Dev Biol. 1988 Oct;129(2):350-7. doi: 10.1016/0012-1606(88)90382-x.
We have examined the levels of glycyl-, alanyl-, and seryl-tRNA synthetases and the levels of their corresponding translatable mRNAs in the posterior and middle silkglands of the silkworm, Bombyx mori. Analysis of Western blots reveals that the change in the abundance of these enzymes during the fifth instar in crude extracts derived from posterior and middle silkgland correlates with changes in enzymatic activity; most of the change in activity for seryl- and alanyl-tRNA synthetases can be accounted for by the corresponding change in enzyme concentration, while the apparent specific activity of glycyl-tRNA synthetase appears to be elevated in the posterior silkgland. Accompanying the changes in enzyme activity and enzyme concentration are changes in the levels of the corresponding mRNAs as determined by immunoprecipitation of in vitro translation products. The levels of all three enzymes are 10 to 20 times higher in the posterior and middle silkglands than in ovarian tissue. A form of alanyl-tRNA synthetase with a slightly higher apparent molecular weight is detected in the posterior silkgland early in the fifth instar and in ovarian tissue.
我们检测了家蚕（Bombyx mori）后部和中部丝腺中甘氨酰 -、丙氨酰 - 和丝氨酰 - tRNA合成酶的水平以及它们相应的可翻译mRNA的水平。蛋白质免疫印迹分析表明，在五龄期，从后部和中部丝腺获得的粗提物中这些酶丰度的变化与酶活性的变化相关；丝氨酰 - 和丙氨酰 - tRNA合成酶活性的大部分变化可由酶浓度的相应变化来解释，而甘氨酰 - tRNA合成酶的表观比活性在后部丝腺中似乎有所升高。通过体外翻译产物的免疫沉淀测定，伴随着酶活性和酶浓度的变化，相应mRNA的水平也发生了变化。后部和中部丝腺中所有这三种酶的水平比卵巢组织中的高10至20倍。在五龄期早期的后部丝腺和卵巢组织中检测到一种表观分子量略高的丙氨酰 - tRNA合成酶形式。
