Fig. 1. Immunoblots of extracts of unstimulated MTLn3 cells with antibodies against tropomyosin. The positions of TM2 and TM5a standards in relation to the bands of the blots are indicated. The f9d antibody recognizes long and short tropomyosin isoforms encoded by the TM and ßTM genes. These include, from top to bottom, TM1 and TM6 (not distinguishable on this blot), TM2, TM3, and minor amounts of short isoforms. The TM311 antibody shows the presence of at least three high molecular weight isoforms: TM1/6, TM2 and TM3. The CGß6 antibody identifies the two faster migrating major forms seen in the f9d and TM311 blots as TM2 and TM3. The blots using LC24 and CG3 recognize the major short tropomyosins expressed in MTLn3 cells as TM4 and one or more products of the TM gene.