We have identified and characterized two proteins in rat brain that bind to the neuron-specific tropomyosin isoform, TMBr3. The two proteins were identified by blot overlay assay, in which the proteins immobilized on the membrane were probed by epitope-tagged TMBr3, followed by detection with anti-epitope antibody. We have purified these proteins using a TMBr3 affinity column. Peptide sequencing as well as immunoblotting showed that one of the two proteins is identical to tropomodulin, a tropomyosin-binding protein originally identified in erythrocytes. The cDNA for the other protein was cloned from an adult rat brain cDNA library using degenerate oligonucleotides that we designed based on the peptide sequences. Sequence analysis of the cDNA clone revealed this protein to be a novel isoform of tropomodulin which is the product of a distinct gene, and is herein referred to as N-tropomodulin. Recombinant N-tropomodulin bound to TMBr3 as well as to other low molecular mass tropomyosins (TM5a or TM5), but not to high molecular mass tropomyosins (TM2 or TMBr1). Northern blotting and RNase protection assays as well as immunoblotting showed that N-tropomodulin is expressed predominantly in brain. Furthermore, RNase protection assays revealed no alternatively spliced regions within the coding sequence. Developmentally, N-tropomodulin was detected in rat brain as early as embryonic day 14 and reaches the adult level before birth. Immunofluorescence of primary frontal cortex cell cultures showed that N-tropomodulin is specifically expressed in neurons. The neuron-specific expression of N-tropomodulin strongly suggests specialized roles of this TM-binding protein in neurons.
N-tropomodulin: a novel isoform of tropomodulin identified as the major binding protein to brain tropomyosin
A. Watakabe, R. Kobayashi, D.M. Helfman; N-tropomodulin: a novel isoform of tropomodulin identified as the major binding protein to brain tropomyosin. J Cell Sci 1 September 1996; 109 (9): 2299–2310. doi: https://doi.org/10.1242/jcs.109.9.2299
Download citation file:
JCS Journal Meeting 2023: Imaging Cell Dynamics
Our 2023 Journal Meeting on ‘Imaging Cell Dynamics’ will be held from 14-17 May 2023 in Lisbon, Portugal. Due to popular demand, we can currently only accept applications for online attendance. Apply now to attend this meeting virtually. Registration deadline: 31 March.
Call for papers: Cell and Tissue Polarity
We are welcoming submissions for our next special issue, which will focus on ‘Cell and tissue polarity’ and will be guest edited by David Bryant. Submission deadline: 15 July.
Editorial: Publishing where it matters
Editor-in-Chief Michael Way outlines Journal of Cell Science’s plans for the upcoming year and introduces Seema Grewal as our new Executive Editor.
preLights 5th Birthday webinar
preLights, our preprint highlighting service, is celebrating its 5th birthday this year. To mark the occasion, join us online on 14 March 2023 at 16:00 GMT for a discussion, led by four preLights alumni, on how to identify and navigate the challenges and opportunities while shaping your career as an early-career researcher.
Cell Scientists to Watch
As a community-focused journal, Journal of Cell Science is keen to support the next generation of cell biologists. Check out Cell Scientists to Watch, our interview series featuring talented researchers who have recently set up their own labs.