Variations in the level of enzyme activity and immunolocalization of calcium-dependent protein kinases in the phloem of different cucumber organs

Kumar, Suresh KG and Jayabaskaran, Chelliah (2004) Variations in the level of enzyme activity and immunolocalization of calcium-dependent protein kinases in the phloem of different cucumber organs. In: Journal of Plant Physiology, 161 (8). pp. 889-901.

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Abstract

Calcium-dependent protein kinases (CDPKs) constitute a unique family of enzymes in plants that are characterized by a C-terminal calmodulin (CaM)-like domain. Through protein kinase assays, we have examined the levels of cucumber calcium-dependent kinase $(C_SCDPK)$ activity in various organs of cucumber seedlings and plants. The activity of $C_SCDPK$ was highest in cucumber plant leaves followed by seedling roots and hypocotyls; however, cucumber plant flowers, seedling cotyledons, and hooks had levels that were barely detectable. The $C_SCDPKs$ were immunolocalized using polyclonal antibodies that are highly specific against a part of the kinase domain of a calcium-dependent protein kinase $(C_SCDPKS)$ in the phloem sieve elements (SEs) in various organs of cucumber. In addition, this study indicates the presence of CsCDPKs in organelle-like bodies associated with the plasma membrane of sieve elements in mature stems and roots as well as in the storage bodies of immature seeds. These findings are discussed in terms of the likely roles played by CDPKs in the signal transduction pathways for $Ca^{2+}$-regulated phloem transport of assimilates from leaves to various organs during growth and development of cucumber seedlings and plants.

Item Type:	Journal Article
Publication:	Journal of Plant Physiology
Publisher:	Elsevier
Additional Information:	The copyright of this article belongs to Elsevier.
Keywords:	Calcium-dependent protein kinases;Cucumber plant and seedling;Phloem transport;Sieve elements
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	09 Apr 2006
Last Modified:	19 Sep 2010 04:25
URI:	http://eprints.iisc.ac.in/id/eprint/6182

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