Structural Proteins of the Mouse Spermatozoan Tail: An Electrophoretic Analysis

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Abstract
Structural components of the mouse spermatozoan tail were resolved into multiple polypeptide species by using 1 and 2-dimensional polyacrylamide gel electrophoresis. Spermatozoa were decapitated by brief incubation with either sodium dodecyl sulfate (SDS, 1%) or trypsin (0.1 mg/ml). The SDS- and trypsin-cleaved spermatozoa were subsequently separated into Pure head and tail fractions by using sucrose gradient centrifugation and ultracentrifugation in a 40-60% metrizamide gradient, respectively. Analysis of the SDS-insoluble structural tail proteins from trypsin-cleaved and SDS-cleaved spermatozoa by single dimension SDS-polyacrylamide gel electrophoresis revealed approximately 20 protein bands. Following exposure to trypsin several of the high MW components were either reduced in quantity or lost completely. When SDS-insoluble tail proteins were carboxymethylated. The complexity of the polypeptide profile diminished substantially, indicating that some high MW bands represented protein aggregation caused by intermolecular disulfide bonds. Isoelectric focusing (IEF) gels of aminoethylated and carboxymethylated tail proteins also resulted in remarkably different banding patterns. Two-dimensional electrophoresis of the structural tail proteins, reduced and carboxymethylated, enabled definitive resolution of 29 major protein spots.