We determined the isoforms of tropomyosin expressed and the level of tropomyosin phosphorylation in donor, end-stage failing and hypertrophic obstructive cardiomyopathy samples of human heart muscle. Western blots and isoform-specific antibodies showed that α-tropomyosin was the only significant isoform expressed and that tropomyosin was 25-30 % phosphorylated at serine 283. Mass spectrometry confirmed directly that α-tropomyosin made up over 95 % of tropomyosin but also indicated the presence of up to 4 % κ-tropomyosin and much smaller amounts of β-, γ- and smooth β-tropomyosin and about 26 % phosphorylation. Neither the isoform distribution nor the level of phosphorylation changed significantly in the pathological heart muscle samples.
Bibliographical noteFunding Information:
Acknowledgments We thank Jim Lin and Peter Gunning for advice with the isoform-specific antibodies and Robin Maytum for help with identifying tropomyosin isoforms. Human samples were provided by Prof William McKenna and Prof Cristobal Dos Remedios. This work was supported by grants from the British Heart Foundation. DGW and mass spectrometry equipment funded by Birmingham Science City.
- Cardiac muscle
- Heart failure
ASJC Scopus subject areas
- Cell Biology