Plant calreticulin is specifically and efficiently phosphorylated by protein kinase CK2.
Calreticulin isolated from spinach leaves has been specifically phosphorylated in vitro by protein kinase CK2 while animal calreticulin from rabbit liver is not a substrate of this kinase under the same conditions. Phosphoserine is the only phosphoamino acid detected. High affinity binding (Km = 4.4 microM) and a nearly stoichiometric incorporation of phosphate was determined. Partially purified spinach calreticulin is phosphorylated at the same site(s) by a copurifying protein kinase sharing biochemical properties very similar if not identical to those of mammalian CK2. Other plant calreticulins isolated from Liriodendron tulipifera appear to be also phosphorylated by CK2.
Baldan
B
B
Dipartimento di Biologia, Università di Padova, Italy.
Navazio
L
L
Friso
A
A
Mariani
P
P
Meggio
F
F
D000595:Amino Acid Sequence; D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D037282:Calreticulin; D047390:Casein Kinase II; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D018724:Spinacia oleracea / Q000378:metabolism*; D013215:Starfish; D013379:Substrate Specificity
D002135:Calcium-Binding Proteins; D037282:Calreticulin; D012261:Ribonucleoproteins; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases