Fig. 4. Differences in selective pressures on the two functional domains of myosin. Sequence relatedness analysis using the entire amino acid sequence for the fast/developmental MYH genes generated different phylogenetic relationships for (A) the myosin head or motor domain, amino acid residues 1-841, and (B) the -helical coiled-coil rod or tail domain, residues 842 to approximately 1938. The motor sequences were more similar to the adult fast MYH genes, indicative of both the role of the MYH13 gene in the superfast contractions of extraocular muscle and the two regions of exon homology evident in Fig. 1. In contrast, the rod domain exhibited a closer relationship to the and ß cardiac sequences, reaffirming the inference that MYH13 diverged and specialized before the precursors of the slow/cardiac and fast/developmental clusters had significantly diverged. This is a modified version of a figure from Briggs and Schachat (2000). emb, embryonic; PN, perinatal.

Return to article