Evidence for the presence of two Homer 1 transcripts in skeletal and cardiac muscles

A family of proteins, Homers 1, 2 and 3, involved in activity-dependent con trol of signal transduction has been recently described in neurons [Xiao, B ., Tu, C. J., Petralia, R. S., Yuan, J. P., Dean, A., Breder, C. D., Ruggie ro, A., Lanahan, A. A., Wenthold, R. J., and Worley, P. F. (1998) Homer reg ulates the association of group 1 metabotropic glutamate receptors with mul tivalent complexes of Homer-related, synaptic proteins. Neuron 21, 107-716] . By RT-PCR and RNasePA, mRNAs transcripts for Homer la and Homer 1c, but n ot Homer 1b, are detected in both skeletal and cardiac muscles of the rat. Full-length cloning of Homer 1a and Homer 1c cDNAs has been accomplished: T here is no tissue specificity, by comparing skeletal muscle, cardiac muscle and cerebellum, and there are a few species-specific base substitutions, b y comparing rat and mouse sequences. The regulatory mechanism exerted via t ransition of Homer 1 isoform composition may be operative in striated muscl es. (C) 2000 Academic Press.