Wiley, Molecular Reproduction and Development, 4(54), p. 402-409, 1999
DOI: 10.1002/(sici)1098-2795(199912)54:4<402::aid-mrd11>3.0.co;2-x
Wiley, Molecular Reproduction and Development, 4(54), p. 402-409
DOI: 10.1002/(sici)1098-2795(199912)54:4<402::aid-mrd11>3.3.co;2-o
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We have determined the presence of cysteine in the protein PL-I from the sperm of the surf clam Spisula solidissima. The existence of cysteine in this histone H1-related protein is responsible for its previously described aggregation behavior. The location of this residue, within the trypsin-resistant domain of the protein, has been established. We have also shown that cysteine is ubiquitously present in the PL-I proteins from the sperm of other bivalve mollusks but is absent from other PL of smaller molecular mass (PL-II, PL-III, PL-IV). We have also found cysteine to be present in the PL-I from a tunicate (Chelysoma productum) but absent in a PL-I from a fish (Mullus barbatus). The possible significance of the unusual occurrence of cysteine in these histone-H1-related proteins is discussed.