Chauvière M, Martinage A, Debarle M, Sautière P, Chevaillier P
Laboratoire de Biologie Cellulaire, Université Paris-Val de Marne, Créteil, France.
Eur J Biochem. 1992 Mar 1;204(2):759-65. doi: 10.1111/j.1432-1033.1992.tb16691.x.
In mouse spermatozoa, DNA is compacted by two protamines mP1 and mP2. Protamine mP2 (63 residues) is synthesized in spermatid nuclei as a precursor pmP2 (106 residues) which is subsequently processed at the end of spermiogenesis [Yelick, P.C., Balhorn, R., Johnson, P.A., Corzett, M., Mazrimas, J.A., Kleene, K.C. & Hecht, N.B. (1987) Mol. Cell. Biol. 7, 2173-2179]. Six proteins, three of which were described earlier [Chauvière, M., Martinage, A., Debarle, M., Alimi, E., Sautière, P. & Chevaillier, Ph. (1991) C.R. Acad. Sci. 313, 107-112], have molecular and electrophoretic properties similar to those of pmP2. They were isolated from purified testis nuclei and characterized by amino acid composition, N-terminal sequence and peptide mapping. From the amino acid compositions, it appears that all six proteins are rich in arginine, cysteine and histidine and are closely related to pmP2 and mP2. The N-terminal sequence of each protein overlaps a distinct region of the N-terminal part of pmP2. The C-terminal part of protamine mP2 starting at arginine 15 is common to all proteins as assessed by amino acid compositions and peptide maps. All these structural data demonstrate that the six isolated proteins are products of pmP2 precursor processing. The six intermediate proteins pmP2/5, pmP2/11, pmP2/16, pmP2/20, pmP2/26 and pmP2/32 which contain 102, 96, 91, 87, 81 and 75 residues, respectively, are generated from the pmP2 precursor after N-terminal excision of 4, 10, 15, 19, 25 and 31 residues, respectively. The C-terminal sequence of protamine mP2 is strictly identical to that of its precursor; therefore, no maturation occurs in this part of the molecule. At the present time, the proteolytic pathway involved in the amino-terminal processing leading to the mature form of the protamine mP2 (63 residues) has not been elucidated. However, the different representation of six intermediates in the testis suggests that some stages of processing are faster than others or that some cleavage sites are preferred. The proteins described in this paper could result either from stepwise excision of N-terminal residues or from non-sequential cleavages.
在小鼠精子中，DNA由两种鱼精蛋白mP1和mP2压缩。鱼精蛋白mP2（63个残基）在精子细胞核中以前体pmP2（106个残基）的形式合成，随后在精子发生结束时进行加工[耶利克，P.C.，巴尔霍恩，R.，约翰逊，P.A.，科尔泽特，M.，马兹里马斯，J.A.，克莱内，K.C.和赫克特，N.B.（1987年）《分子细胞生物学》7，2173 - 2179]。有六种蛋白质，其中三种先前已有描述[肖维耶，M.，马丁纳热，A.，德巴勒，M.，阿利米，E.，索蒂埃，P.和谢瓦利耶，Ph.（1991年）《法国科学院院报》313，107 - 112]，它们的分子和电泳性质与pmP2相似。它们从纯化的睾丸细胞核中分离出来，并通过氨基酸组成、N端序列和肽图谱进行表征。从氨基酸组成来看，似乎所有六种蛋白质都富含精氨酸、半胱氨酸和组氨酸，并且与pmP2和mP2密切相关。每种蛋白质的N端序列与pmP2 N端部分的一个不同区域重叠。通过氨基酸组成和肽图谱评估，鱼精蛋白mP2从精氨酸15开始的C端部分是所有蛋白质共有的。所有这些结构数据表明，分离出的六种蛋白质是pmP2前体加工的产物。六种中间蛋白pmP2/5、pmP2/11、pmP2/16、pmP2/20、pmP2/26和pmP2/32分别含有102、96、91、87、81和75个残基，它们是在分别从pmP2前体的N端切除4、10、15、19、25和31个残基后产生的。鱼精蛋白mP2的C端序列与其前体的C端序列完全相同；因此，该分子的这一部分没有发生成熟过程。目前，导致鱼精蛋白mP2（63个残基）成熟形式的N端加工所涉及的蛋白水解途径尚未阐明。然而，睾丸中六种中间体的不同表现表明，某些加工阶段比其他阶段快，或者某些切割位点更受青睐。本文所述的蛋白质可能是由N端残基的逐步切除或非顺序切割产生的。
