Protein expression of myosin IC isoforms A and B in mammalian cell lines.

Detection of myosin IC isoforms A and B protein in various mammalian cell lines by immunoblot analysis using antibodies specific to myosin IC isoforms A, isoform B, SV40 large T-antigen (TAg) and actin (control). A) Schematic of myosin IC isoform specific sequences and recognition site of antibodies. Depicted is the 5′ region of the mammalian MYOIC gene with the exons that code for isoform specific N-terminal peptides. The translation start sites for the isoforms are indicated as are the N-terminal amino acid sequences. Underlined are the peptide sequences used as immunogen to create isoform-specific antibodies. B) Representative immunoblot of cell extracts that were analyzed using the indicated antibodies. Relevant molecular weight markers are indicated on the left in kD. C) Histogram presenting the average densitometric intensity of myosin IC isoform A expression normalized to actin. D) Histogram presenting the average densitometric intensity of isoform B expression normalized to actin. Myosin IC isoform A protein is highly expressed in COS-7 cells and the human and mouse prostate cancer cell lines PC-3 and TRAMP-C2. In contrast, myosin IC isoform B protein is expressed at comparable levels in all analyzed cell lines. Results are presented as means ± standard deviation; n = 3 independent experiments.