14-3-3 alpha and delta are the phosphorylated forms of raf-activating 14-3-3 beta and zeta. In vivo stoichiometric phosphorylation in brain at a Ser-Pro-Glu-Lys MOTIF.
The 14-3-3 protein family has received considerable attention recently in the literature, because of the finding that beta and zeta isoforms interact with and activate Raf. We had previously shown that these 14-3-3 isoforms also exist as phosphorylated forms in mammalian and avian brain. The presence of this modification enhances the activity of 14-3-3 as an inhibitor of protein kinase C nearly 2-fold. In this report we show by a combination of electrospray mass spectrometry and protein microsequencing that alpha and delta are in vivo post-translationally modified forms of beta and zeta, respectively, and the site of phosphorylation, serine 185, is in a consensus sequence motif for proline-directed kinases.
Aitken
A
A
Laboratory of Protein Structure, National Institute for Medical Research, Mill Hill, London, United Kingdom.
Howell
S
S
Jones
D
D
Madrazo
J
J
Patel
Y
Y
D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002645:Chickens; D007527:Isoenzymes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D046911:Macromolecular Substances; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010748:Phosphopeptides / Q000737:chemistry / Q000302:isolation & purification; D010750:Phosphoproteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf; D012756:Sheep; D014446:Tyrosine 3-Monooxygenase
D048948:14-3-3 Proteins; D007527:Isoenzymes; D046911:Macromolecular Substances; D010748:Phosphopeptides; D010750:Phosphoproteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D014446:Tyrosine 3-Monooxygenase; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf