PP4R4/KIAA1622 Forms a Novel Stable Cytosolic Complex with Phosphoprotein Phosphatase 4

The inositol polyphosphate 4-phosphatase forms a complex with phosphatidylinositol 3-kinase in human platelet cytosol.

Inositol polyphosphate 4-phosphatase (4-phosphatase) is an enzyme that catalyses the hydrolysis of the 4-position phosphate from phosphatidylinositol 3,4-bisphosphate [PtdIns(3,4)P2]. In human platelets the formation of this phosphatidylinositol, by the actions of phosphatidylinositol 3-kinase (PI 3-kinase), correlates with irreversible platelet aggregation. We have shown previously that a phos...

Characterization of a novel alkaline phosphatase activity which co-purifies with a phosphorylase (phosphoprotein) phosphatase of Mr = 35,000 cardiac muscle.

In a previous communication (Li, H.-C., Hsiao, K.-J., and Chan, W. W. S. (1978) Eur. J. Biochem 84,215-225) we reported the purification of a divalent cation-independent, nonspecific phosphoprotein phosphatase (phosphatase S, M, = 35,000) from canine cardiac muscle to apparent homogeneity. It was found that the homogeneous enzyme preparation exhibited significant activity toward p-nitrophenyl p...

Phosphoprotein pp65 UL97 Forms a Complex with the Tegument Human Cytomegalovirus Protein Kinase

Human cytomegalovirus protein kinase UL97 forms a complex with the tegument phosphoprotein pp65.

UL97 is a protein kinase encoded by human cytomegalovirus (HCMV) and is an important target for antiviral drugs against this ubiquitous herpesvirus, which is a major cause of life-threatening opportunistic infections in the immunocompromised host. In an effort to better understand the function(s) of UL97 during HCMV replication, a recombinant HCMV, NTAP97, which expresses a tandem affinity puri...

A phosphoprotein phosphatase from ox brain.

1. The pyrophosphate-exchange reactions which are catalysed by rat-liver preparations and depend upon leucine or isoleucine are profoundly modified by 'soluble' ribonucleic acid and by changes in magnesium concentration. The preponderant influence is exerted by the terminal nucleotide sequence of the 'soluble' ribonucleic acid. Lysinedependent pyrophosphate exchange occurs only at relatively hi...