Meiosis-specific protein selectively associated with sex chromosomes of rat pachytene spermatocytes.
During the first meiotic prophase of mammalian spermatogenesis, the sex chromosomes X and Y show a characteristic allocyclic behavior with respect to the autosomes. This is particularly evident during pachytene stage when sex chromosomes form the so-called sex vesicle. This structure is characterized by the condensed state of chromatin, transcriptional inactivity, and the limited extension of chromosome pairing, which is usually restricted to a short segment of sex chromosome axial elements. The molecular basis and functional significance of sex vesicle formation during mammalian spermatogenesis remain obscure. Here we report on the identification of a meiosis-specific sex vesicle protein we called XY40. Immunocytochemical localization on rat testis cryosections with a XY40-specific monoclonal antibody revealed that the labeling is confined to the axial elements of sex chromosomes. Biochemical characterization showed that protein XY40 (40 kDa; pI 5.7-5.8) can be extracted from rat pachytene spermatocytes and recovered in particles of 9.5 S with a native molecular mass of approximately 152 kDa. We speculate that protein XY40 may be involved in the allocyclic behavior of sex chromosomes during male meiotic prophase.
Smith
A
A
Department of Zoology I, University of Würzburg, Federal Republic of Germany.
Benavente
R
R
D000818:Animals; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D002499:Centrifugation, Density Gradient; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D008297:Male; D009687:Nuclear Proteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D013090:Spermatocytes / Q000166:cytology / Q000502:physiology*; D013091:Spermatogenesis; D014960:X Chromosome; D014998:Y Chromosome
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D009687:Nuclear Proteins