Disease relevance of Syntide-2

• Although recombinant CaMKIx expressed in Escherichia coli showed no protein kinase activity against syntide-2, a synthetic peptide substrate, it was activated when phosphorylated by mouse Ca(2+)/calmodulin-dependent protein kinase kinase alpha (CaMKKalpha) [1].

High impact information on Syntide-2

• NR2B inhibits both the Ca(2+)/calmodulin-dependent and autonomous activities of CaMKII by a mechanism that is competitive with autocamtide-2 substrate, non-competitive with syntide-2 substrate, and uncompetitive with respect to ATP [2].
• In contrast, addition of purified PKCepsilon to the incubation mixture induced rapid Ser(744) and Ser(748) phosphorylation, concomitant with persistent 2-3-fold increases in PKD activity, measured using reimmunoprecipitated PKD to phosphorylate an exogenous peptide, syntide-2 [3].
• Deletion of the entire PH domain (amino acids 429-557) markedly increased the basal activity of the enzyme as assessed by autophosphorylation ( approximately 16-fold) and exogenous syntide-2 peptide substrate phosphorylation assays (approximately 12-fold) [4].
• The kinetics of bacterially expressed human CaMKI show that the peptide syntide-2 is a relatively poor substrate, whereas the synapsin site-1 peptide is 17-fold more specific [5].
• Our results demonstrate that bombesin rapidly induces PKD activation in Swiss 3T3 cells, as shown by autophosphorylation and syntide-2 phosphorylation assays [6].

Biological context of Syntide-2

• CaMK-(281-309), but not CaMK-(281-289), bound calmodulin and was a potent inhibitor (IC50 = 0.88 +/- 0.7 microM using 20 microM syntide-2) of exogenous substrate (syntide-2 or glycogen synthase) phosphorylation by a completely Ca2+/calmodulin-independent form of the kinase generated by limited proteolysis with chymotrypsin [7].
• Based on molecular mass, calcium/calmodulin-dependent autophosphorylation, substrate specificity, KN-62 inhibition, apparent Km for ATP and syntide-2, these proteins were identified as calcium/calmodulin-dependent protein kinase II (CaM kinase II) [8].
• This kinase phosphorylates the synthetic peptides such as syntide 2, autocamtide-2, site 3 in a Ca2+/CaM-dependent manner, but not myosin light chain-peptide, gamma-peptide, and cAMP Response Element Binding Protein (CREB) peptide [9].

Anatomical context of Syntide-2

• Ionomycin treatment of these cells resulted in increased kinase activity of cytosolic extracts toward syntide-2, a synthetic peptide substrate for calcium/calmodulin-dependent kinase II (CaM-KII), with kinetics similar to those of CD20 phosphorylation in the cell line [10].
• The immunoprecipitates with the antibodies from K562 cells phosphorylates the synthetic peptide substrates, syntide-2 [11].
• PKD expressed in COS cells showed syntide-2 kinase activity that was stimulated by phorbol esters in the presence of phospholipids [12].
• The motility of demembranated spermatozoa at 30 degrees C remained high in control samples and following the addition of Kemptide, Syntide 2 and PKC substrate peptide, but decreased markedly following the addition of MLCK substrate peptide [13].
• Biochemical analyses showed that NtCPK4 phosphorylated itself and calf thymus histones fraction III-S (histone III-S) in a calcium-dependent manner, and the K0.5 of calcium activation was 0.29 microM or 0.25 microM with histone III-S or syntide-2 as substrates, respectively [14].

Associations of Syntide-2 with other chemical compounds

• The addition of [3H]phorbol 12,13-dibutyrate, 1-oleoyl-2-acetylglycerol, or 1,2-dioctanoyl-sn-glycerol in the presence of dioleoylphosphatidylserine stimulated the syntide-2 kinase activity of PKD in a synergistic fashion (4-6-fold) [15].
• Here, we show that substitution of Ser744 and Ser748 with alanine (PKD-S744A/S748A) completely blocked PKD activation induced by phorbol-12,13-dibutyrate (PDB) treatment of intact cells as assessed by autophosphorylation and exogenous syntide-2 peptide substrate phosphorylation assays [16].
• As judged by the Vmax/KM ratios (0.5 for PKCmu and 2.2 for PKCzeta) the substrate syntide 2 is phosphorylated by suramin-activated PKCzeta around four times more effectively than by suramin-activated PKCmu [17].
• Resveratrol was comparably effective against PKD autophosphorylation (IC(50) = 52 microM) and PKD phosphorylation of the exogenous substrate syntide-2 (IC(50) = 36 microM) [18].

Gene context of Syntide-2

• PKD prepared by elution from immunoprecipitates with the immunizing peptide efficiently phosphorylated the synthetic peptide syntide-2 [15].
• Activation of CaM-kinase IV resulted in a 10-fold decrease in Km for syntide-2 with little effect on Km for ATP or Vmax [19].
• The optimum concentration of poly(Lys) for the phosphorylation of 1 microM CaM was about 10 microg/ml, but poly(Lys) strongly inhibited CaM-kinase IV activity toward syntide-2 at this concentration, suggesting that the phosphorylation of CaM is not due to simple activation of the catalytic activity [20].
• The CaM kinase V had an apparent Km for ATP of 75 +/- 11 microM and for syntide-2 of 20 +/- 4 microM [21].
• Kinetic analysis showed that the kinase not previously autophosphorylated had a Km for the synthetic peptide syntide-2 of 7 microM and Vmax of 9.8 mumol/min/mg when assayed in the presence of Ca2+ and CaM [22].

References