Kistler W S, Henriksén K, Mali P, Parvinen M
Department of Anatomy, University of Turku, Finland.
Exp Cell Res. 1996 Jun 15;225(2):374-81. doi: 10.1006/excr.1996.0188.
Transition proteins and protamines are highly basic sperm-specific nuclear proteins that serve to compact the DNA during late spermiogenesis. To understand their sequential role in this function, transition protein 1 (TP1), transition protein 2 (TP2), and protamine 1 (P1) were assayed by polyacrylamide gel electrophoresis in pools of microdissected, staged seminiferous tubule segments in the rat. The results were compared with immunocytochemical analyses of squash preparations from accurately identified stages of the epithelial cycle. TP2 was the first to appear as a faint band at stages IX-XI, followed by high levels at stages XII-XIV of the cycle. TP1 showed a low expression at stage XII of the cycle and peaked at stages XIII-I, whereas protamine 1 first appeared at stage I of the cycle and remained high throughout the rest of spermiogenesis. Immunocytochemical analyses and Western blots largely confirmed these results: TP2 in steps 9-14, TP1 in steps 12-15, and P1 from late step 11 to step 19 of spermiogenesis. We propose that TP2 is the first nucleoprotein that replaces histones from the spermatid nucleus, and its appearance is associated with the onset of nuclear elongation. TP1 shows up along with the compaction of the chromatin. The two transition proteins seem to have distinct roles during transformation of the nuclei and compaction of spermatid DNA.
过渡蛋白和鱼精蛋白是高度碱性的精子特异性核蛋白，在精子发生后期用于压缩DNA。为了解它们在该功能中的顺序作用，通过聚丙烯酰胺凝胶电泳对大鼠显微切割的、分期的生精小管片段池中的过渡蛋白1（TP1）、过渡蛋白2（TP2）和鱼精蛋白1（P1）进行了检测。将结果与来自上皮周期准确识别阶段的压片制备物的免疫细胞化学分析进行了比较。TP2是第一个在IX-XI期以 faint带出现的，随后在周期的XII-XIV期水平升高。TP1在周期的XII期表达较低，在XIII-I期达到峰值，而鱼精蛋白1首先在周期的I期出现，并在精子发生的其余阶段保持高水平。免疫细胞化学分析和蛋白质免疫印迹在很大程度上证实了这些结果：精子发生的第9-14步中有TP2，第12-15步中有TP1，第11步后期到第19步中有P1。我们提出TP2是第一个从精子细胞核中取代组蛋白的核蛋白，其出现与核伸长的开始有关。TP1随着染色质的压缩而出现。这两种过渡蛋白在细胞核转化和精子细胞DNA压缩过程中似乎具有不同的作用。
