Tropomyosin-binding properties of the CHASM protein are dependent upon its calponin homology domain.
The calponin homology-associated smooth muscle protein (CHASM) can modulate muscle contractility, and its biological action may involve an interaction with the contractile filament. In this study, we demonstrate an interaction between CHASM and tropomyosin. Deletion constructs of CHASM were generated, and pull-down assays revealed a minimal deletion construct that could bind tropomyosin. Removal of the calponin homology (CH) domain or expression of the CH domain alone did not enable binding. The interaction was characterized by microcalorimetry with a dissociation constant of 2.0x10(-6) M. Confocal fluorescence microscopy also showed green fluorescent protein (GFP)-CHASM localization to filamentous structures within smooth muscle cells, and this targeting was dependent upon the CH domain.
Ulke-Lemée
Annegret
A
Department of Biochemistry and Molecular Biology, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta, Canada T2N 4Z6.
Ishida
Hiroaki
H
Borman
Meredith A
MA
Valderrama
Alexandra
A
Vogel
Hans J
HJ
MacDonald
Justin A
JA
D000595:Amino Acid Sequence; D000818:Animals; D002135:Calcium-Binding Proteins / Q000737:chemistry*; D002151:Calorimetry; D007082:Ileum / Q000378:metabolism; D042541:Intracellular Space / Q000378:metabolism; D008840:Microfilament Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry* / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014020:Tissue Extracts; D014335:Tropomyosin / Q000378:metabolism*; D000096985:Calponins
D002135:Calcium-Binding Proteins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D010750:Phosphoproteins; D014020:Tissue Extracts; D014335:Tropomyosin; D000096985:Calponins; C491838:SMTNL1 protein, mouse