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Figure 3.
Fig. 3. Structural variations in the C-terminal region of
different vertebrate Tm isoforms. (A) Coiled-coil predictions,
using the program COILS (28-29) (with a 14-residue window size)
for the C-terminal regions of the products of the  -Tm gene.
In striated-muscle -Tm,
encoded by exon 9a (red squares), the coiled-coil propensity
decreases sharply after Gln-263, consistent with a 22-residue
splayed region observed in the current study (see Materials and
Methods). Vertebrate smooth-muscle -Tm and
many nonmuscle isoforms, encoded by exon 9d (green circles), are
also predicted to be -helical
but not in a two-stranded coiled-coil conformation at the C
terminus. However, the coiled coil in these isoforms appears to
extend beyond residue 262 to at least residue 270. In the brain
isoforms, TmBr-1 and TmBr-3, encoded by exon 9c (dotted line),
the C terminus is predicted to be an -helical
coiled coil to the very end. In another brain isoform, TmBr-2,
encoded by exon 9b (solid line), the C-terminal region is mostly
likely not -helical
because of three closely spaced prolines. (B) Schematic
representation of the C-terminal ends of striated- and
smooth-muscle -Tms.
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