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Abnormal thiol reactivity of tropomyosin in essential hypertension and its association with abnormal sodium-lithium countertransport kinetics

Lookup NU author(s): Dr Sharlene Watkins, Dr Ian West, Professor Robert Wilkinson, Dr Trevor Thomas


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Objectives: To identify a thiol protein that is abnormal in a subgroup of essential hypertensive (EHT) patients who have a strong family history of hypertension and cardiovascular disease and have a low Km of erythrocyte Na/Li countertransport (CT). Methods: To detect biotin maleimide labelling of a key thiol protein to investigate its reaction with N-ethylmaleimide (NEM) in normal and EHT erythrocytes. Results: The thiol protein of 33 kDa apparent molecular weight (p33) identified by the loss of labelling with biotin maleimide was identified as tropomyosin due to its retarded running in 6 mol/I urea gels and immunoblotting. The NEM reaction with p33 detected by loss of subsequent biotin maleimide labelling is biphasic in normal control erythrocytes with the rate in the first 30 s double that after 30 s. In EHT erythrocytes NEM reaction (1) after 30 s is faster than normal and (2) in the first 30 s causes a paradoxical increase in apparent biotin maleimide labelling. In normal control erythrocytes, the loss of biotin maleimide labelling with NEM reaction or the faster phenylmaleimide reaction follows the same time course as the decrease in Km of Na/Li CT. Conclusions: NEM reaction with p33 requires two thiols. Only the cytoskeletal form of tropomyosin from the TM3 gene has more than one thiol group and agrees with SDS-PAGE mobility. Tropomyosin is a strong candidate to explain the familial abnormality in EHT with abnormal Na/Li CT and it could explain many of the characteristics of this disease. © 2001 Lippincott Williams & Wilkins.

Publication metadata

Author(s): Thomas TH; Wilkinson R; West IC; Watkins SL

Publication type: Article

Publication status: Published

Journal: Journal of Hypertension

Year: 2001

Volume: 19

Issue: 3

Pages: 485-493

Print publication date: 01/01/2001

ISSN (print): 0263-6352

ISSN (electronic): 1473-5598

Publisher: Lippincott Williams & Wilkins


DOI: 10.1097/00004872-200103000-00017

PubMed id: 11288819


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