Calmodulin content, Ca2+-dependent calmodulin binding proteins, and testis growth: Identification of Ca2+-dependent calmodulin binding proteins in primary spermatocytes

Abstract

In contrast with the transient pre‐replicative increase in calmodulin (CaM) level observed in proliferative activated cells, postnatal development of rat testis was paralleled by 3 specific rises in CaM. The first one occurred between 5 and 10 days, coincident with the appearance and proliferation start of spermatogonia and Sertoli cells. Meiosis accomplishment and spermatid differentiation were paralleled by 2 additional rises, at 24 and 32 days, respectively. The plateau phase of testis growth was coincident with the appearance of maturating spermatids and spermatozoa in the germinal epithelium, and with a decrease in CaM content. Testicular DNA:g wet tissue ratio reached the highest level in 15‐day‐old rats and gradually decreased up to 35 days, when a constant level was reached. A similar level of Ca2+‐CaMBPs was observed in 5‐ and 20‐day‐old rat testis. Although all subcellular fractions showed the ability to bind CaM in a Ca2+‐dependent manner, CaM was mainly recovered in the nuclear and soluble fractions of adult and immature rat testis. Several Ca2+‐CaMBPs with an apparent Mr of 82, 75, 64, 19, and 14 kD were purified by affinity chromatography from pachytene primary spermatocyte nuclear matrix. Ca2+‐CaMBPs showing an Mr of 120, 78, 72, and 66 kD were also purified from the supernatant obtained after DNA and RNA hydrolysis of meiotic nuclei. Major cytosolic Ca2+‐CaMBPs of primary spermatocytes showed an Mr of 120, 84, 44, and 39 kD. The functions that these Ca2+‐CaMBPs might have during the first meiotic prophase is discussed. Mol. Reprod. Dev. 48:127–136, 1997. © 1997 Wiley‐Liss, Inc.

Evidence that the PERF 15 Germ Cell Specific Protein Associates with DNA in the Presence of Ca2+

“…The interaction between PERF 15 and DNA was confirmed by DNA-cellulose binding assay. In the previous studies of calmodulin, the protein-protein interactions were analyzed in the presence of 1-2 mM Ca 2+ (Moriya et al, 1993;Trejo and Delhumeau, 1997). Therefore, DNA-cellulose binding assay was also performed at a concentration of either 0 or 1 mM Ca 2+ .…”