The Occurrence of a Gene-Encoded Variant of Nuclear Basic Protein (SP4) in Sperm of Xenopus laevis

• Published in: Biochemical and biophysical research communications 1995-09, Vol.214 (2), p.622-626
• Main Authors: Takamune, K., Teshima, K., Abe, S.I., Katagiri, C.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Chromatography, High Pressure Liquid; Genetic Variation; Male; Molecular Sequence Data; Nuclear Proteins - biosynthesis; Nuclear Proteins - chemistry; Nuclear Proteins - genetics; Peptide Fragments - chemistry; Peptide Fragments - isolation & purification; Sequence Homology, Amino Acid; Spermatozoa - metabolism; Xenopus laevis - genetics; Xenopus Proteins
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1995.2331

In our recent analyses [1] of five tandemly arranged genes encoding a major sperm-specific basis nuclear protein (SP4) of Xenopus laevis, we found a gene containing a single base substitution which will give rise to the replacement of the 69th residue among the 78 amino acids of SP4. In this study, the polypeptide from sperm nuclei which were separated by reversed-phase HPLC as a distinct entity from SP4 were collected for their peptide mapping with V8 protease and partial amino acid sequence analyses. It resulted that a polypeptide exhibiting an amino acid replacement at exactly the same position as predicted from a single base substitution of SP4 occurs in approximately one-fourth of the amount of SP4. This finding suggests that the relative amount of SP4 and its variant directly depends on the relative number of genes of SP4 and its variant.