Targeting of a tropomyosin isoform to short microfilaments associated with the Golgi complex

Percival , Justin M., Hughes, Julie A. I., Brown, Darren L., Schevzov, Galina, Heimann, Kirsten, Vrhovski, Bernadette, Bryce, Nicole, Stow , Jennifer L., and Gunning, Peter W. (2004) Targeting of a tropomyosin isoform to short microfilaments associated with the Golgi complex. Molecular Biology of the Cell, 15 (1). pp. 268-280.

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Abstract

A growing body of evidence suggests that the Golgi complex contains an actin-based filament system. We have previously reported that one or more isoforms from the tropomyosin gene Tm5NM (also known as gamma-Tm), but not from either the alpha- or beta-Tm genes, are associated with Golgi-derived vesicles (Heimann et al., (1999). J. Biol. Chem. 274, 10743-10750). We now show that Tm5NM-2 is sorted specifically to the Golgi complex, whereas Tm5NM-1, which differs by a single alternatively spliced internal exon, is incorporated into stress fibers. Tm5NM-2 is localized to the Golgi complex consistently throughout the G1 phase of the cell cycle and it associates with Golgi membranes in a brefeldin A-sensitive and cytochalasin D-resistant manner. An actin antibody, which preferentially reacts with the ends of microfilaments, newly reveals a population of short actin filaments associated with the Golgi complex and particularly with Golgi-derived vesicles. Tm5NM-2 is also found on these short microfilaments. We conclude that an alternative splice choice can restrict the sorting of a tropomyosin isoform to short actin filaments associated with Golgi-derived vesicles. Our evidence points to a role for these Golgi-associated microfilaments in vesicle budding at the level of the Golgi complex.

Item ID: 323
Item Type: Article (Refereed Research - C1)
Keywords: constitutive transport vesicles, messenger-RNA, myosin-II, endoplasmic-reticulum, molecular composition, actin microfilaments, proteins, identification, localization, muscle
ISSN: 1939-4586
Date Deposited: 14 Sep 2006
FoR Codes: 06 BIOLOGICAL SCIENCES > 0699 Other Biological Sciences @ 0%
06 BIOLOGICAL SCIENCES > 0601 Biochemistry and Cell Biology @ 0%
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