Light- and calcium-modulated phosphorylation of proteins from wheat seedlings

Sharma, Vijay K. ; Jain, Pradeep K. ; Malik, Mukesh K. ; Maheshwari, Satish C. ; Khurana, Jitendra P. (1997) Light- and calcium-modulated phosphorylation of proteins from wheat seedlings Phytochemistry, 44 (5). pp. 781-786. ISSN 0031-9422

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In vivo white light irradiation (for 1 hr or more) of four-day-old etiolated wheat seedlings followed by in vitro phosphorylation decreased the phosphorylation of 52 and 48 kDa polypeptides in the proteins of the soluble fraction; short pulses of white light or red/far-red were not effective. Studies using norflurazon, a bleaching herbicide, suggest that dephosphorylation of this polypeptide may be linked with light-dependent development of plastids. Studies employing a Ca2+ chelator, EGTA, and several calmodulin (CaM) inhibitors indicate that phosphorylation of 52, 48, 34 and 31 kDa polypeptides, both in the dialysed and undialysed soluble fractions, is Ca2+---CaM dependent. The depletion of Ca2+ also retarded the mobility of a 52 kDa polypeptide by 4-6 kDa, particularly in the undialysed fraction, which was restored to control level by increasing the Ca2+ level, a property unique to Ca2+-binding proteins. Strikingly, the phosphorylation status of a doublet (17 and 15 kDa phosphopolypeptides), visible primarily in the dialysed fraction, was not affected by light and/or Ca2+---CaM antagonists. The results suggest the existence of Ca2+/CaM-dependent protein kinase(s) in young wheat seedlings, whose activity, directly or indirectly, is down-regulated by white light.

Item Type:Article
Source:Copyright of this article belongs to Phytochemical Society of Europe.
ID Code:18703
Deposited On:17 Nov 2010 12:33
Last Modified:06 Jun 2011 11:31

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