Phosrestide-1, a peptide derived from the Drosophila photoreceptor protein phosrestin I, is a potent substrate for Ca2+/calmodulin-dependent protein kinase II from rat brain.
Multifunctional Ca2+/calmodulin-dependent protein kinase type II (CaMK II) plays a crucial role in mediation of cellular responses to rising cytosolic Ca2+ levels. We find that the novel peptide substrate PGTIEKKRSNAMKKMKSIEQHR serves as a highly potent substrate for CaMK II enzymes purified from both Drosophila and rat. The peptide is derived from a photoreceptor-specific protein, phosrestin I, of the Drosophila compound eye and is designated as phosrestide-1. Using saturating substrate concentrations, the enzymes from both species transfer the gamma-phosphoryl group of ATP to phosrestide-1 at a level three to ten times greater than to the commercially available mammalian-derived CaMK II substrates, autocamtide-3 and syntide-2. This indicates a conservation of substrate preferences for CaMK II derived from distantly related species, a dipteran fly and a mammal. Although phosrestide-1 contains two potential serine residues for CaMK II phosphorylation, we find that only the C-terminal serine is phosphorylated by rat CaMK II. However, removal of the upstream sequence containing the N-terminal serine substantially reduced the potency of phosrestide-1 as a CaMK II substrate to a level comparable to that of syntide-2 or autocamtide-3. We also find that a peptide representing the N-terminal segment of phosrestide-1 does not inhibit either CaMK II. Therefore, the enhanced potency of phosrestide-1 as a CaMK II substrate is likely to be due to a preferred conformation of the peptide induced by the N-terminal segment rather than to a specific binding of the enzymes to the N-terminus of the peptide. To the best of our knowledge, phosrestide-1 is the first CaMK II substrate which is designed based on an invertebrate sequence. The high phosphorylation level of phosrestide-1 by CaMK II of mammalian origin may reflect highly conserved CaMK II signaling cascades between vertebrates and invertebrates.[1]References
- Phosrestide-1, a peptide derived from the Drosophila photoreceptor protein phosrestin I, is a potent substrate for Ca2+/calmodulin-dependent protein kinase II from rat brain. Kahn, E.S., Kinumi, T., Tobin, S.L., Matsumoto, H. Comp. Biochem. Physiol. B, Biochem. Mol. Biol. (1998) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
