1. Spermatid-specific expression of the novel X-linked gene product SPAN-X localized to the nucleus of human spermatozoa
- Author
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V A, Westbrook, A B, Diekman, K L, Klotz, V V, Khole, C, von Kap-Herr, W L, Golden, R L, Eddy, T B, Shows, M H, Stoler, C Y, Lee, C J, Flickinger, and J C, Herr
- Subjects
Cell Nucleus ,Male ,X Chromosome ,Base Sequence ,Transcription, Genetic ,Genetic Linkage ,Molecular Sequence Data ,Chromosome Mapping ,Nuclear Proteins ,Haploidy ,Blotting, Northern ,Spermatids ,Recombinant Proteins ,Meiosis ,Testis ,Humans ,Amino Acid Sequence ,Isoelectric Point ,RNA, Messenger ,In Situ Hybridization - Abstract
Formation of mature spermatozoa involves a series of dramatic molecular and morphological changes in the male germ cell lineage. These changes result from the temporally regulated transcription and translation of several testis-specific gene products. Here, we describe a novel, testis-specific protein designated SPAN-X for sperm protein associated with the nucleus on the X chromosome. SPAN-X sequences showed no significant similarity with known cDNA or peptide sequences. The SPAN-X peptide sequences contained three overlapping consensus nuclear localization signals, a high percentage (33%-37%) of charged amino acid residues, and a relatively acidic isoelectric point (pI; 4.88-6.05). Northern analysis of mRNA from multiple human tissues identified a SPAN-X transcript exclusively in the testis. In situ hybridization of human testes sections showed SPAN-X mRNA expression in haploid, round, and elongating spermatids. The SPANX gene was mapped to chromosome Xq27. 1 by fluorescence in situ hybridization and by Southern blot analysis of human/mouse somatic cell hybrids. On Western blots of human sperm proteins, antirecombinant SPAN-X antibodies reacted with broad bands migrating between 15-20 kDa. Immunofluorescent labeling of human spermatozoa demonstrated SPAN-X localization to nuclear craters and cytoplasmic droplets. Expression of SPAN-X, an X-linked gene product, exclusively in haploid spermatids leads to interesting questions regarding the transcription of sex-linked genes during spermiogenesis.
- Published
- 2000