Casein kinases phosphorylate multiple residues spanning the entire hnRNP K length.
Heterogeneous Nuclear Ribonucleoprotein K (hnRNP K) is an RNA/DNA-binding protein involved in many processes that regulate gene expression. K protein's pleiotropic action reflects the diversity of its molecular interactions. Many of these interactions have been shown to be regulated by phosphorylation. K protein contains more than seventy potential phosphorylation sites. We used an integrated approach of mass spectrometry and computer analysis to explore patterns of K protein phosphorylation. We found that in vitro a single kinase can phosphorylate K protein on multiple sites spanning the entire length of the protein, including residues contained within the RNA/DNA-binding domains. 2-D gel electrophoresis of K protein purified from cells identified 5-8 spots. Mass spectrometry of K protein isolated from proliferating cells and from cells under oxidative stress revealed the same pattern of phosphopeptides. The structural implications of phosphorylation are discussed.
Mikula
Michał
M
Institute of Oncology, 02-781 Warsaw, Poland.
Karczmarski
Jakub
J
Dzwonek
Artur
A
Rubel
Tymon
T
Hennig
Ewa
E
Dadlez
Michał
M
Bujnicki
Janusz M
JM
Bomsztyk
Karol
K
Ostrowski
Jerzy
J
D000595:Amino Acid Sequence; D000818:Animals; D047388:Casein Kinases / Q000737:chemistry*; D034641:Heterogeneous-Nuclear Ribonucleoprotein K / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011487:Protein Conformation; D051381:Rats
D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D047388:Casein Kinases