The Caenorhabditis elegans gene unc-89, required for muscle M-line assembly, encodes a giant modular protein composed of Ig and signal transduction domains

• Type of Material: Article
• Authors: Guy Benian, Emory University; Tina L. Tinley, Emory University; Xuexin Tang, Emory University; Mark Borodovsky, Emory University
• Language: English
• Date: 1996-03-01
• Publisher: Rockefeller University Press
• Publication Version: Final Published Version
• Copyright Statement: © The Rockefeller University Press.
• Final Published Version (URL): http://dx.doi.org/10.1083/jcb.132.5.835
• Title of Journal or Parent Work: Journal of Cell Biology
• ISSN: 0021-9525
• Volume: 132
• Issue: 5
• Start Page: 835
• End Page: 848
• Grant/Funding Information: This work was supported in part by the National Institutes of Health (NIH) (to G.M. Benian and M. Borodovsky). Some nematode strains were provided by the Caenorhabditus Genetics Center, which is funded by the NIH National Center for Research Resources.
• Keywords: TITIN; GLOBULAR HEAD; Life Sciences & Biomedicine; MOTIFS; LOCALIZATION; Cell Biology; SEQUENCE; M-BAND; Science & Technology; NEUROFILAMENT SUBUNIT; C C-PROTEIN; DBL-ONCOGENE PRODUCT; LIGHT CHAIN KINASE
• Research Categories: Biology, Cell; Health Sciences, Pathology

Abstract

Mutations in the Caenorhabditis elegans gene unc-89 result in nematodes having disorganized muscle structure in which thick filaments are not organized into A-bands, and there are no M-lines (Waterston, R.H., J.N. Thomson, and S. Brenner. 1980. Dev. Biol. 77:271-302). Beginning with a partial cDNA from the C. elegans sequencing project, we have cloned and sequenced the unc-89 gene. An unc-89 allele, st515, was found to contain an 84-bp deletion and a 10-bp duplication, resulting in an in-frame stop codon within predicted unc-89 coding sequence. Analysis of the complete coding sequence for unc-89 predicts a novel 6,632-amino acid polypeptide consisting of sequence motifs which have been implicated in protein protein interactions. UNC-89 begins with 67 residues of unique sequence, SH3, db1/CDC24, and PH domains, 7 immunoglobulin (Ig) domains, a putative KSP- containing multiphosphorylation domain, and ends with 46 Ig domains. A polyclonal antiserum raised to a portion of unc-89 encoded sequence reacts to a twitchin-sized polypeptide from wild type, but truncated polypeptides from st515 and from the amber allele e2338. By immunofluorescent microscopy, this antiserum localizes to the middle of A-bands, consistent with UNC-89 being a structural component of the M-line. Previous studies indicate that myofilament lattice assembly begins with positional cues laid down in the basement membrane and muscle cell membrane. We propose that the intracellular protein UNC-89 responds to these signals, localizes, and then participates in assembling an M-line.