Stratifin, a keratinocyte specific 14-3-3 protein, harbors a pleckstrin homology (PH) domain and enhances protein kinase C activity

Elena Dellambra, Mauro Patrone, Bianca Sparatore, Armando Negri, Fabrizio Ceciliani, Sergio Bondanza, Francesco Molina, Fiorella Descalzi Cancedda, Michele De Luca

Risultato della ricerca: Contributo su rivistaArticolo in rivistapeer review

Abstract

The intrinsic signal(s) responsible for the onset of human keratinocyte terminal differentiation is not yet fully understood. Evidence has been recently accumulated linking the phospholipase-mediated activation of protein kinase C to the coordinate changes in gene expression occurring during keratinocyte terminal differentiation. Here we report the purification of a keratinocyte-derived protein enhancing protein kinase C enzymatic activity. The stimulator eluted as a peak with estimated molecular mass of approximately 70 kDa, while analysis by SDS-PAGE showed a 30 kDa protein migrating as a distinct doublet, suggesting the formation of a 30 kDa homodimer. The amino acid sequence analysis allowed the unambigous identification of the protein kinase C stimulator as a mixture of the highly homologous σ (stratifin) and ζ isoforms of 14-3-3 proteins, which are homodimers of identical 30 kDa subunits. Mono Q anion exchange chromatography and immunoblot analysis further confirmed that stratifin enhances protein kinase C activity. Stratifin was originally sequenced from a human keratinocyte protein database, but its function was unknown. The pleckstrin homology domain has been recently related to protein translocation to the cell membrane as well as to functional interactions of intracellular proteins involved in signal transduction. We show here that stratifin (and 14-3-3 ζ) harbors a pleckstrin homology domain, and the consequent functional implications will be discussed.

Lingua originaleInglese
pagine (da-a)3569-3579
Numero di pagine11
RivistaJournal of Cell Science
Volume108
Numero di pubblicazione11
Stato di pubblicazionePubblicato - nov 1995
Pubblicato esternamente

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