RT Journal Article SR Electronic T1 Tropomyosin isoforms in rat neurons: the different developmental profiles and distributions of TM-4 and TMBr-3 are consistent with different functions JF Journal of Cell Science JO J. Cell Sci. FD The Company of Biologists Ltd SP 2961 OP 2973 VO 107 IS 10 A1 Had, L. A1 Faivre-Sarrailh, C. A1 Legrand, C. A1 Mery, J. A1 Brugidou, J. A1 Rabie, A. YR 1994 UL http://jcs.biologists.org/content/107/10/2961.abstract AB Antipeptide antisera specific for TM-4 and TMBr-3, the two tropomyosin isoforms in neurons, were used to investigate the concentrations and distributions of these F-actin-binding proteins in neurons in vitro and in vivo. TM-4 and TMBr-3 tropomyosins had different developmental profiles. TM-4 was found mainly in immature stages, while the concentration of TMBr-3 increased with maturation. The two isoforms also had different subcellular distributions. TM-4 was concentrated in the growth cones of cultured neurons and, in vivo, in areas where neurites were growing. Later, when development was complete, TM-4 was restricted to postsynaptic sites in the cerebellar cortex, whereas TMBr-3 was found in the presynaptic terminals. These data suggest that the tropomyosin isoforms have different functions, through their interaction with the actin cytoskeleton. TM-4 may be involved in the motile events of neurite growth and synaptic plasticity, while TMBr-3 could play a role in stabilizing neuronal networks and synaptic functioning.