Anti-PKDREJ (cytoplasmic domain) polyclonal antibody

Sea urchin spermatozoa are model cells for studying signal transduction events underlying flagellar motility and the acrosome reaction. We previously described the sea urchin sperm receptor for egg jelly 1 (suREJ1) which consists of 1450 amino acids, has one transmembrane segment and binds to the fucose sulfate polymer of egg jelly to induce the sperm acrosome reaction. We also cloned suREJ3 which consists of 2681 amino acids and has 11 putative transmembrane segments. Both these proteins localize to the plasma membrane over the acrosomal vesicle. While cloning suREJ1, we found suREJ2, which consists of 1472 amino acids, has two transmembrane segments and is present in the entire sperm plasma membrane, but is concentrated over the sperm mitochondrion. Experimental evidence suggests that, unlike suREJ1 and suREJ3, suREJ2 does not project extracellularly from the plasma membrane, but is an intracellular plasma membrane protein. All three sea urchin sperm REJ proteins possess a protein module of > 900 amino acids, termed 'the REJ module', that is shared by the human autosomal dominant polycystic kidney disease protein, polycystin-1, and PKDREJ, a testis-specific protein in mammals whose function is unknown. In the present study, we describe the sequence, domain structure and localization of suREJ2 and speculate on its possible function.

Complementary molecules on the surface of both gametes are responsible for the interaction of sperm protein receptors with zona pellucida (ZP) saccharide structures, and many primary sperm receptors for ZP glycoproteins have been disclosed in various mammals. For our study, proteins were obtained from the surface of ejaculated and in vitro capacitated boar sperm. The isolated proteins were characterized by 1D- and 2D-electrophoretic protein profiles, and by glycoprotein staining. Our results show quantitative and qualitative differences in protein and glycoprotein patterns between ejaculated and capacitated sperm. Far-western blotting with ZP glycoproteins identified 17 interactions in the subproteome of the ejaculated sperm and 14 interactions in the subproteome of the capacitated sperm. High-molecular-mass proteins, coincident with binding to ZP, were sequence-identified. Angiotensin-converting enzyme (ACE), polycystic kidney disease receptor and egg jelly receptor (PKDREJ), and acrosin precursor were successfully identified. This is the first time PKDREJ has been identified on the surface of boar spermatozoa. (C) 2013 Elsevier B.V. All rights reserved.