Zalenskaia I A, Odintsova N A, Zalenskiĭ A O, Vorob'ev V I
Mol Biol (Mosk). 1982 Mar-Apr;16(2):335-44.
Composition of basic chromosomal proteins from sperm of the bivalve mollusc Swiftopecten swifti is specific: (1) somatic histone H1 is replaced for a sperm-specific one containing three subfractions, enriched in Arg; (2) low molecular weight sperm-specific basic protein (S protein) is present in the chromatin additionally to the histones. It is shown that chromatin from the mollusc sperm has typical nucleosomal organization, however the DNA repeat length is markedly increased (225 bp) on account of the linker region of the nucleosome. It is found using two-dimensional electrophoresis that fraction of the mononucleosomes is heterogeneous and represented by four electrophoretic subfractions which differ in protein composition and length of DNA they contain. Subfraction which differ in protein composition and length of DNA they contain. Subfractions of mononucleosomes in the order of increase of electrophoretic mobility contain along with core histones: (1)--all H1 subfractions, protein X, protein S; (2)--subfraction H1"', protein X, protein S; (3)--protein S. The particles containing only core histones correspond to the most rapidly migrating band. The data show that protein S is, like histone H1, possibly bound to the linker DNA. Interdependence between the presence of sperm-specific non-core (-linker?) proteins, the increase in size of linker DNA and compaction of sperm chromatin is suggested.
（1）体细胞组蛋白H1被一种含三个亚组分且富含精氨酸的精子特异性组蛋白所取代；（2）除组蛋白外，染色质中还存在低分子量精子特异性碱性蛋白（S蛋白）。研究表明，软体动物精子的染色质具有典型的核小体结构，然而由于核小体的连接区，DNA重复长度显著增加（225 bp）。通过二维电泳发现，单核小体部分是异质的，由四个电泳亚组分组成，它们在蛋白质组成和所含DNA长度上有所不同。按照电泳迁移率增加的顺序，单核小体的亚组分除核心组蛋白外还含有：（1）——所有H1亚组分、蛋白X、蛋白S；（2）——H1'''亚组分、蛋白X、蛋白S；（3）——蛋白S。仅含核心组蛋白的颗粒对应迁移最快的条带。数据表明，蛋白S可能像组蛋白H1一样与连接DNA结合。研究提出了精子特异性非核心（-连接？）蛋白的存在、连接DNA大小的增加与精子染色质压缩之间的相互关系。
