N. Bonafe et Jr. Sellers, MOLECULAR CHARACTERIZATION OF MYOSIN-V FROM DROSOPHILA-MELANOGASTER, Journal of muscle research and cell motility, 19(2), 1998, pp. 129-141
Recent studies have revealed unconventional myosin V to be an importan
t actin-based molecular motor involved in vesicular movement. In this
paper we report the molecular characterization of the Drosophila myosi
n V, identified by reverse genetics. The gene encodes a 1792-residue,
207 kDa heavy chain polypeptide which possesses a typical head or moto
r domain of 771 residues, a region of six IQ motifs (139 residues) whi
ch serve as potential calmodulin/light chain binding sites at the head
/ tail junction, and a tail domain of 882 residues containing sequence
s of putative alpha-helical coiled-coils required for dimerization of
the molecule and sequences of non-helical structure at the C-terminal
end. Based on Southern blot analyses and chromosomal localization, evi
dence is presented for a single Drosophila myosin V gene. RNA analyses
revealed a doublet of transcripts of about 6 kb, expressed throughout
the lifetime of a fly but particularly abundant in the early stages o
f embryonic development (maternally contributed), in the ectodermic ti
ssue of the hindgut starting at stage 16, and in the adult head. These
results suggest that myosin V may be involved in processes required i
n a variety of cell types in Drosophila. We have also mapped the Droso
phila myosin V locus to chromosome 2 at the position 43C-D, and we are
currently searching for known mutations in this region. Finally, phyl
ogenetic analysis of the head domain reveals that Drosophila myosin V
is more closely related to mammalian myosin Va and Vb than to other in
vertebrate class-V myosins; nevertheless, it is not significantly more
related to myosin Va than to myosin Vb. While vertebrates would need
two different myosin V isoforms to accomplish specific functions, we s
peculate that Drosophila myosin V might provide the equivalent functio
ns by itself. (C) Chapman & Hall Ltd.