asynchronous oscillatory contraction of fly wings

Some unassigned signals were observed that may correspond to some degradation
species.

Assignment of the 1H, 13C, and 15N resonances of holo isoform 4 of Lethocerus indicus troponin C.

The indirect flight muscles (IFMs) of Lethocerus (giant water bug) and
Drosophila (fruitfly) are asynchronous: oscillatory contractions are produced
by periodic stretches in the presence of a Ca(2+) concentration that does not
fully activate the muscle. The troponin complex on thin filaments regulates
contraction in striated muscle. The complex in IFM has subunits that are
specific to this muscle type, and stretch activation may act through troponin.
Lethocerus and Drosophila have an unusual isoform of the Ca(2+)-binding subunit
of troponin, troponin C (TnC), with a single Ca(2+)-binding site near the
C-terminus (domain IV); this isoform is only in IFMs, together with a minor
isoform with an additional Ca(2+)-binding site in the N-terminal region (domain
II). Lethocerus has another TnC isoform in leg muscle which also has two
Ca(2+)-binding sites. Ca(2+) binds more strongly to domain IV than to domain II
in two-site isoforms. There are four isoforms in Drosophila and Anopheles
(malarial mosquito), three of which are also in adult Lethocerus. A larval
isoform has not been identified in Lethocerus. Different TnC isoforms are
expressed in the embryonic, larval, pupal and adult stages of Drosophila; the
expression of the two IFM isoforms is increased in the pupal stage.
Immunoelectron microscopy shows the distribution of the major IFM isoform with
one Ca(2+)-binding site is uniform along Lethocerus thin filaments. We suggest
that initial activation of IFM is by Ca(2+) binding to troponin with the
two-site TnC, and full activation is through the action of stretch on the
complex with the one-site isoform.

Qiu F, Lakey A, Agianian B, Hutchings A, Butcher GW, Labeit S, Leonard K,
Bullard B.
Troponin C in different insect muscle types: identification of two isoforms in
Lethocerus, Drosophila and Anopheles that are specific to asynchronous flight
muscle in the adult insect.
Biochem J. 2003 May 1; 371(Pt 3): 811-21.

Troponin C in different insect muscle types: identification of two isoforms in Lethocerus, Drosophila and Anopheles that are specific to asynchronous flight muscle in the adult insect.

This is the theoretical mass of the sequence without the two additional
residues (GA) added N-terminally for purification purposes.

Solution Structure Of Fly Troponin C, Isoform F1

pet24d(M11) vector containing an N-terminal hexahistidine tag followed by a TEV
protease cleavage site.

1H, 13C and 15N chemical shift assignment of fly troponin C

simulated annealing, torsion angle dynamics