Flightin is essential for thick filament assembly and sarcomere stability in Drosophila flight muscles.


Journal Article

Flightin is a multiply phosphorylated, 20-kD myofibrillar protein found in Drosophila indirect flight muscles (IFM). Previous work suggests that flightin plays an essential, as yet undefined, role in normal sarcomere structure and contractile activity. Here we show that flightin is associated with thick filaments where it is likely to interact with the myosin rod. We have created a null mutation for flightin, fln(0), that results in loss of flight ability but has no effect on fecundity or viability. Electron microscopy comparing pupa and adult fln(0) IFM shows that sarcomeres, and thick and thin filaments in pupal IFM, are 25-30% longer than in wild type. fln(0) fibers are abnormally wavy, but sarcomere and myotendon structure in pupa are otherwise normal. Within the first 5 h of adult life and beginning of contractile activity, IFM fibers become disrupted as thick filaments and sarcomeres are variably shortened, and myofibrils are ruptured at the myotendon junction. Unusual empty pockets and granular material interrupt the filament lattice of adult fln(0) sarcomeres. Site-specific cleavage of myosin heavy chain occurs during this period. That myosin is cleaved in the absence of flightin is consistent with the immunolocalization of flightin on the thick filament and biochemical and genetic evidence suggesting it is associated with the myosin rod. Our results indicate that flightin is required for the establishment of normal thick filament length during late pupal development and thick filament stability in adult after initiation of contractile activity.

Full Text

Cited Authors

  • Reedy, MC; Bullard, B; Vigoreaux, JO

Published Date

  • December 25, 2000

Published In

Volume / Issue

  • 151 / 7

Start / End Page

  • 1483 - 1500

PubMed ID

  • 11134077

Pubmed Central ID

  • 11134077

International Standard Serial Number (ISSN)

  • 0021-9525

Digital Object Identifier (DOI)

  • 10.1083/jcb.151.7.1483


  • eng

Conference Location

  • United States