COMPARATIVE IMMUNOGOLD ANALYSIS OF TUBULIN ISOFORMS IN THE MOUSE SPERM FLAGELLUM - UNIQUE DISTRIBUTION OF GLUTAMYLATED TUBULIN

The distribution of different tubulin isoforms in the mouse sperm flag ellum was studied using four site-directed antibodies to tubulin: DM1A and DM1B general anti alpha and beta-tubulin, 6-11B-1 anti-acetylated alpha-tubulin, and GT335 anti-glutamylated alpha and beta-tubulin. Qu antitative immunogold analyses were performed on five regions of the f lagellum: the middle piece, three successive regions of the principal piece, and the terminal piece. A uniform labeling was observed with DM 1A and DM1B along the entire flagellum both for peripheral doublets an d the central pair. Similar results were obtained with 6-11B-1 directe d to acetylated alpha-tubulin, an N-terminal-modified tubulin isoform. In contrast, the labeling for glutamylated alpha and beta-tubulin, C- terminal modified isoforms, was not uniform. The highest intensity was found in the middle piece and the terminal piece. The labeling which decreased significantly both for peripheral doublets and central pair along the principal piece was considered as a loss of glutamylated tub ulin accessibility. From the middle piece to the end of the principal piece, this labeling was predominant in doublets 1-5-6, corresponding to the plane of the flagellar wave. However, the labeling for doublets 2-3-4-7-8-9 was heterogeneous, showing an increasing asymmetry. These results suggest that in the mammalian sperm cell model, the glutamyla ted tubulin might be involved in a functional heterogeneity among peri pheral doublets of the flagellum. (C) 1996 Wiley-Liss, Inc.