Phosphorylation of human placenta membrane calpactins with bovine brain protein kinase C

1990 ◽  
Vol 18 (4) ◽  
pp. 586-587
Author(s):  
JUNOR A. BARNES ◽  
MORLEY D. HOLLENBERG
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Human Placenta ◽  
Bovine Brain ◽  
Brain Protein ◽  
Kinase C ◽  
Placenta Membrane

Simultaneous phosphorylation of three human calpactins by kinase C

1991 ◽  
Vol 69 (2-3) ◽  
pp. 163-169 ◽  
Author(s):  
Junor A. Barnes ◽  
Dennis Michiel ◽  
Morley D. Hollenberg
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Molecular Mass ◽  
Key Words ◽  
Bovine Brain ◽  
Related Protein ◽  
Brain Protein ◽  
Kinase C ◽  
High Calcium ◽  
Intracellular Compartments

We evaluated the concurrent phosphorylation of reconstituted mixtures of three purified human placental calpactins (or lipocortins) by purified bovine brain protein kinase C (PKC). Calpactin-I (p36 or lipocortin-II), calpactin-II (p38 or lipocortin-I), and a 70-kilodalton calpactin-related protein, calpactin-p70, when present together as substrates for PKC, all demonstrated comparable kinetic parameters (Vmax values = 0.3–0.5 nmol phosphate incorporated/min), with calpactin-II and calpactin-p70 exhibiting lower apparent Km values (40 and 30 nM, respectively) than did calpactin-I (Km, 200 nM). Because of the higher Vmax/Km ratios for calpactin-II and calpactin-70 (12.5 and 10.0, respectively) compared with the ratio for calpactin-I (2.0), our data suggest that, intracellularly, where all three calpactins might be co-localized, the higher molecular mass calpactins could be preferred substrates for PKC. Nonetheless, the requirement for relatively high calcium concentrations (≥ 0.5 mM) suggests that PKC-mediated phosphorylation of the calpactins may take place only in restricted intracellular compartments, wherein calcium concentrations might transiently reach levels much higher than those that are normally found intracellularly (≤ 0.25 mM).Key words: calpactins, kinase C, lipocortins, phosphorylation.

scholarly journals Substitution of phosphatidylserine by lipid A in the activation of purified rabbit brain protein kinase C

FEBS Letters ◽  
1987 ◽  
Vol 218 (2) ◽  
pp. 238-242 ◽  
Author(s):  
Christine A. Ellis ◽  
Alastair Aitken ◽  
Kuni Takayama ◽  
Nilofer Qureshi
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Lipid A ◽  
Rabbit Brain ◽  
Brain Protein ◽  
Kinase C
Sign in / Sign up

Export Citation Format

Share Document