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A critical beta6-beta7 loop in the pleckstrin homology domain of ceramide kinase.

Rovina, Philipp, Jaritz, Markus, Hoefinger, Siegfried, Graf, Christine, Devay, Piroska, Billich, Andreas, Baumruker, Thomas and Bornancin, Frederic (2006) A critical beta6-beta7 loop in the pleckstrin homology domain of ceramide kinase. The Biochemical Journal, 400 (2). pp. 255-265. ISSN 1470-8728


CerK (ceramide kinase) produces ceramide 1-phosphate, a sphingophospholipid with recognized signalling properties. It localizes to the Golgi complex and fractionates essentially between detergent-soluble and -insoluble fractions; however, the determinants are unknown. Here, we made a detailed mutagenesis study of the N-terminal PH domain (pleckstrin homology domain) of CerK, based on modelling, and identified key positively charged amino acid residues within an unusual motif in the loop interconnecting beta-strands 6 and 7. These residues are critical for CerK membrane association and polyphosphoinositide binding and activity. Their mutagenesis results in increased thermolability, sensitivity to proteolysis, reduced apparent molecular mass as well as propensity of the recombinant mutant protein to aggregate, indicating that this loop impacts the overall conformation of the CerK protein. This is in contrast with most PH domains whose function strongly relies on charges located in the beta1-beta2 loop.

Item Type: Article
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Keywords: ceramide kinase; ceramide 1-phosphate; Golgi complex; pleckstrin homology domain (PH domain); polyphosphoinositide; subcellular localization
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Date Deposited: 14 Dec 2009 13:56
Last Modified: 31 Jan 2013 01:11