RABBIT SKELETAL-MUSCLE ALPHA-ALPHA-TROPOMYOSIN EXPRESSED IN BACULOVIRUS-INFECTED INSECT CELLS POSSESSES THE AUTHENTIC N-TERMINUS STRUCTURE AND FUNCTIONS
L. Kluwe et al., RABBIT SKELETAL-MUSCLE ALPHA-ALPHA-TROPOMYOSIN EXPRESSED IN BACULOVIRUS-INFECTED INSECT CELLS POSSESSES THE AUTHENTIC N-TERMINUS STRUCTURE AND FUNCTIONS, Journal of muscle research and cell motility, 16(2), 1995, pp. 103-110
When expressed in E, coli, skeletal muscle alpha-tropomyosin has an un
acetylated N-terminus. Unacetylated alpha-tropomyosin lacks important
functions; this is non-polymerizable and has a low affinity to actin.
In the present work, in order to obtain fully functional recombinant a
lpha-tropomyosin, rabbit skeletal muscle alpha-tropomyosin (alpha-trop
omyosin(BV)) has been expressed in baculovirus-infected insect cells.
alpha-Tropomyosin(BV) was not distinguishable from the authentic tropo
myosin, not only in functional properties but also in blocked N-termin
us. To know the N terminus structure of alpha-tropomyosin(BV), the N-t
erminal segment six amino acids long, MDAIKK, has been specifically an
d efficiently removed from alpha-tropomyosin(BV) by use of an immobili
zed proteolytic enzyme system based on E, coli cell bodies which carry
the ompT gene product, a proteolytic enzyme localized on the outer ce
ll wall of E, coli. The structure of recombinant alpha-tropomyosin(BV)
was shown to be identical to the authentic protein by electrospray ma
ss spectrometry and protein sequencing analysis. Additionally, electro
spray mass spectometry indicated a single phosphorylation not only in
alpha- but also beta-tropomyosin chains in the rabbit skeletal muscle.
The differentiated susceptibilities of potential ompT cleavage sites
are indicative of a non-coiled-coil conformation of the N-terminus of
alpha-tropomyosin.