Fig. 1. Specific expression of RIM-BP3 in the mouse testis. (A) The RIM-BP3 protein showing the conserved domains and three antigen regions for raising antibodies. (B) Northern hybridization analysis of the RIM-BP3 transcript in different tissues as indicated above. The mRNA blot (Clontech) contains 2 µg mRNA on each lane. The hybridization probe corresponds to the C-terminal coding sequence (nucleotides 3547-4260). (C) Western analysis of the RIM-BP3 protein in different tissues as indicated above. The detection of -tubulin serves as a loading control (lower panel). (D) Western detection of the RIM-BP3 protein in developing postnatal testis. Upper panel, diagram of stages of mouse spermatogenesis; PL, preleptotene spermatocytes; L, leptotene spermatocytes; Z, zygotene spermatocytes; P, pachytene spermatocytes; D, diplotene spermatocytes; MI, meiosis I; MII, meiosis II; middle panel, western analysis of RIM-BP3 (0-60 days post partum); bottom panel, Coomassie blue staining of the protein samples. (E) Western detection of RIM-BP3 in purified male germ cells. A, type A spermatogonia; B, type B spermatogonia; RS, round spermatids; E1 and E2, two pools of elongate spermatids; SP, mature sperm; RB, residual bodies; ST, Sertoli cells. Other abbreviations used are as in D. The lower panel shows Coomassie blue staining of samples used for the western analysis.