Proteins of de-membraned protamine-depleted mouse sperm. Homology with proteins of somatic cell nuclear envelope/matrix.

Following treatment with Triton X/1 M NaCl/2-mercaptoethanol, mouse sperm heads are divested of protamines and other basic proteins; the residual structure is one in which the general morphological organization of the decondensed chromatin and the nuclear boundaries are conserved [1]. In this study, the protein complement of that residual structure has been characterized and subdivided into two sets: 1. Those that are sperm-unique, including constituents of the sperm head that may be intrinsically nuclear (or extra-nuclear, but exceedingly adherent to the nuclear envelope). 2. Those that display corresponding electrophoretic properties and immunologic cross-reactivity with proteins of similarly treated mouse somatic cell nuclei. Among the latter are proteins of molecular weight 52, 63 and 69 kD, two of which (63 and 69 kD) appear to be homologous to polypeptides of somatic nuclear envelope/pore complex lamina. Absence from sperm nuclei of the third of the characteristic predominant triplet of somatic nuclear lamina polypeptides of mammalian cells, here designated 67 kD, indicates cell-type variation in these structures. On the other hand, the identification of homologous polypeptides in the sperm and somatic complements suggests that those are specific instances of conservation and may represent the paternal contribution to the pool of polypeptides for assembly of the envelopes of the pronuclei of the one-cell embryo.