Purification procedure and monoclonal antibodies: two instruments for research on vertebrate porins

On Western blots of skeletal muscle preparations of different vertebrate classes, four monoclonal anti-human type 1 porin antibodies recognize one single band of either 30.5 or 31 kDa, respectively. To confirm that it is eukaryotic porin which is labeled by the antibodies, we used a purification procedure developed for human type 1 porin for porins from skeletal muscle of shark, frog, and turkey. Applied to different mammalian species and tissues, this procedure exclusively provides type 1 porin. However, applied to shark skeletal muscle, it provides two porin isotypes in nearly equal amounts. In the case of frog skeletal muscle, the procedure provides mainly type 2 porin and a lower amount of type 1 porin. Applied to turkey skeletal muscle, the method provides exclusively type 2 porin. As demonstrated by two-dimensional Western blots, both shark and frog porin isotypes and the turkey type 2 porin are recognized by our antibodies. Furthermore, we elucidated the entire amino acid sequence of frog type 2 porin.