beta-Scruin, a homologue of the actin crosslinking protein scruin, is localized to the acrosomal vesicle of Limulus sperm.
J Cell Sci, 1995/10;108 ( Pt 10):3155-62.
Way M[1], Sanders M, Chafel M, Tu YH, Knight A, Matsudaira P
Affiliations
PMID: 7593276
Impact factor: 5.235
Abstract
Scruin (alpha-scruin) is an actin bundling protein found in the acrosomal process of Limulus polyhemus sperm. We have cloned and sequenced a second scruin isoform from Limulus, beta-scruin, that is 67% identical to alpha-scruin. Northern and Southern analyses confirm that beta-scruin and alpha-scruin are encoded by distinct genes. The sequence of beta-scruin, like alpha-scruin, is organized into N- and C-terminal superbarrel domains that are characterized by a six-fold repeat of a 50 residue motif. Western analysis using rabbit polyclonal antisera specific for alpha- and beta-scruin indicate that beta-scruin, like alpha-scruin, is found in Limulus sperm but not blood or muscle. Both immunofluorescence microscopy and immunogold-EM localize beta-scruin within the acrosomal vesicle at the anterior of sperm but not in the acrosomal process. The function of beta-scruin in this membrane-bounded compartment that is devoid of actin is unknown. However, the location of beta-scruin together with the fact that it contains two putative beta-superbarrel structural folds, which are known to be catalytic domains in a number of proteins, suggests it may have a possible enzymatic role.
MeSH terms
Acrosome; Actins; Amino Acid Sequence; Animals; DNA, Complementary; Horseshoe Crabs; Male; Molecular Sequence Data; Phylogeny; Rabbits; Sequence Alignment; Sequence Analysis; Spermatozoa
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