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Cotton Bracts Tannin Phosphorylates Airway Membrane Proteins

M.M. Cloutier and L. Guernsey


 
ABSTRACT

In airway epithelial cells, tannin, isolated from cotton bracts, inhibits chloride secretion, decreases $-adrenergic receptor number, uncouples the $-adrenergic receptor from its stimulatory G protein and desensitizes the airway epithelium to $-agonists. We examined the effect of tannin on airway membrane protein phosphorylation, especially phosphorylation of the $-adrenergic receptor as a mechanism of rapid desensitization. Using bovine tracheal epithelial cells, gel electrophoresis and autoradiographic techniques, tannin promotes phosphorylation of 3 distinct membrane proteins, one of which is within the molecular weight range of the $-adrenergic receptor and is phosphorylated rapidly. The pattern and timing of the phosphorylation suggest a role for tannin stimulation of a $-adrenergic receptor kinase ($ARK) in tannin desensitization of airway epithelial cells.



Reprinted from Proceedings of the 1997 Beltwide Cotton Conferences pp. 182 - 185
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998