RIM Is Present In The Human Spermatozoa And Is Involved In The Acrosome Reaction

MAGADAN, J.G.; ROGGERO, CARLOS M.; DE BLAS, GERARDO A.; MAYORGA, LUIS S.; YUNES, ROBERTO

San Carlos de Bariloche. Rio Negro. Argentina

Congreso; XXXIX Reunión Anual de la Sociedad Argentina De Investigación Bioquímica Y Biología Molecular (SAIB); 2003

Acrosome reaction (AR) is a regulated exocytic process, essential during gamete interactions. There is information regarding the role of fusogenic proteins during this exocytosis. One of those proteins is RIM, a putative effector of Rab3A. We used human normal sperm samples (WHO). After swim-up separation, the concentration was adjusted to 7 x 106 cells/ml. Indirect immunofluorescent assay using a polyclonal antibody showed that RIM is present in streptolysin O permeabilized human spermatozoa, and is localized to the acrosome. Additionally, the N-terminal residues 1-399 of RIM inhibited the AR stimulated by calcium in a dose-dependent way. In brief: 1) RIM is present in the acrosomal region in human spermatozoa; 2) the N-terminal portion of RIM inhibits the AR. It is possible to postulate that the lack of the C terminus, where the conspicuous domains C2A and C2B are located, is responsible for the inhibitory effect. We will test this possibility by using the whole molecule from purified brain extracts.