Campus Units

Biochemistry, Biophysics and Molecular Biology, Roy J. Carver Department of

Document Type

Article

Publication Version

Published Version

Publication Date

2007

Journal or Book Title

Journal of Cell Science

Volume

120

Issue

13

First Page

2190

Last Page

2204

DOI

10.1242/jcs.03465

Abstract

Titin, the giant elastic protein found in muscles, is present in spindles of crane-fly and locust spermatocytes as determined by immunofluorescence staining using three antibodies, each raised against a different, spatially separated fragment of Drosophila titin (D-titin). All three antibodies stained the Z-lines and other regions in insect myofibrils. In western blots of insect muscle extract the antibodies reacted with high molecular mass proteins, ranging between rat nebulin (600-900 kDa) and rat titin (3000-4000 kDa). Mass spectrometry of the high molecular mass band from the Coomassie-Blue-stained gel of insect muscle proteins indicates that the protein the antibodies bind to is titin. The pattern of staining in insect spermatocytes was slightly different in the two species, but in general all three anti-D-titin antibodies stained the same components: the chromosomes, prophase and telophase nuclear membranes, the spindle in general, along kinetochore and non-kinetochore microtubules, along apparent connections between partner half-bivalents during anaphase, and various cytoplasmic components, including the contractile ring. That the same cellular components are stained in close proximity by the three different antibodies, each against a different region of D-titin, is strong evidence that the three antibodies identify a titin-like protein in insect spindles, which we identified by mass spectrometry analysis as being titin. The spindle matrix proteins skeletor, megator and chromator are present in many of the same structures, in positions very close to (or the same as) D-titin. Myosin and actin also are present in spindles in close proximity to D-titin. The varying spatial arrangements of these proteins during the course of division suggest that they interact to form a spindle matrix with elastic properties provided by a titin-like protein.

Comments

This article is published as Fabian, Lacramioara, Xuequin Xia, Deepa V. Venkitaramani, Kristen M. Johansen, Jørgen Johansen, Deborah J. Andrew, and Arthur Forer. "Titin in insect spermatocyte spindle fibers associates with microtubules, actin, myosin and the matrix proteins skeletor, megator and chromator." Journal of cell science 120, no. 13 (2007): 2190-2204. doi: 10.1242/jcs.03465. Posted with permission.

Copyright Owner

The Company of Biologists Limited

Language

en

File Format

application/pdf

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