✍ Scribed by Jürgen Soll; Veronika Berger; John Bennett
No coin nor oath required. For personal study only.
A 64-kilodalton (kDa) protein, situated in the lumen between the inner and outer envelopes of pea (Pisum sativum L.) chloroplasts (Soll and Bennett 1988, Eur. J. Biochem., 175, 301-307) is shown to undergo reversible phosphorylation in isolated mixed envelope vesicles. It is the most conspicuously labelled protein after incubation of envelopes with 33 nmol·1(-1) [γ-(32)P]ATP whereas incubation with 50 μmol·1(-1) [γ-(32)P]ATP labels most prominently two outer envelope proteins (86 and 23 kDa). Half-maximum velocity for phosphorylation of the 64-kDa protein occurs with 200 nmol·1(-1) ATP, and around 40 μmol·1(-1) ATP for phosphorylation of the 86- and 23-kDa proteins, indicating the operation of two distinct kinases. GGuanosine-, uridine-, cytidine 5'-triphosphate and AMP are poor inhibitors of the labelling of the 64-kDa protein with [γ-(32)P]ATP. On the other hand, ADP has a potent influence on the extent of labelling (half-maximal inhibition at 1-5 μmol·1(-1)). The ADP-dependent appearance of (32)P in ATP indicates that ADP acts by reversal of kinase activity and not as a competitive inhibitor. However, the most rapid loss of (32)P from pre-labelled 64-kDa protein occurs when envelope vesicles are incubated with ATP t1/2=15 s at 20 μmolsd1(-1) ATP). This induced turnover of phosphate appears to be responsible for the rapid phosphoryl turnover seen in situ.
📜 SIMILAR VOLUMES
HL-60 cells were incubated with ["Pl-P, in order to label endogenous phosphoproteins in situ. These were then resolved via two-dimensional electrophoresis and autoradiograms were made from the gels. A comparison of autoradiograms made from rctinoic-acid-differentiated cells with those made from cont
Phenytoin (PH) is commonly used as an anticonvulsant drug, and it causes several collateral effects including morphological changes in brain cortex neurons and teratogenic lesions in infants of epileptic mothers. Several lines of evidence indicate that PH may exert its action through the modificatio