Saperas N, Chiva M, Bols N C, Kulak D, Kasinsky H E
Biol Bull. 1993 Oct;185(2):186-196. doi: 10.2307/1541999.
Seven basic proteins can be isolated from sperm nuclei of the holocephalan ratfish Hydrolagus colliei. Two of these proteins (R3 and m0) are devoid of cysteine, whereas five of them (R1, R2, m1, m2, and m3) contain low levels of this amino acid residue. The proteins R1, R2, and R3 are major ones in the sperm nuclei of H. colliei, and they are analogous to basic proteins Z1, Z2, and Z3 (scylliorhinines) from the sperm of the elasmobranch Scyliorhinus canicula. However, taking into account the partial sequence of R3 protein and the number of cysteines in R1 and R2, these proteins do not seem to be homologous to the scylliorhinines. A comparison of sperm basic proteins between H. colliei (a holocephalan) and S. canicula (an elasmobranch) suggests a remarkable divergence of these proteins from a common ancestral pattern during the evolution of Chondrichthyes.
从银鲛科海兔（Hydrolagus colliei）的精子细胞核中可以分离出七种碱性蛋白。其中两种蛋白（R3和m0）不含半胱氨酸，而另外五种蛋白（R1、R2、m1、m2和m3）含有少量这种氨基酸残基。蛋白R1、R2和R3是海兔精子细胞核中的主要蛋白，它们类似于软骨鱼纲白斑角鲨（Scyliorhinus canicula）精子中的碱性蛋白Z1、Z2和Z3（角鲨科）。然而，考虑到R3蛋白的部分序列以及R1和R2中的半胱氨酸数量，这些蛋白似乎与角鲨科蛋白不同源。对海兔（一种银鲛科鱼类）和白斑角鲨（一种软骨鱼纲鱼类）精子碱性蛋白的比较表明，在软骨鱼纲的进化过程中，这些蛋白与共同祖先模式有显著差异。
