title: GRP94 (endoplasmin) co-purifies with and is phosphorylated by Golgi apparatus casein kinase.
abstract: A phosphorylatable protein band of about 94 kDa (as judged by SDS-PAGE) which co-purifies and co-immunoprecipitates with Golgi apparatus casein kinase (G-CK) from rat lactating mammary gland has been shown by mass spectrometric sequence analysis to be identical or very similar to the glucose-regulated protein, GRP94. GRP94 is also readily phosphorylated by G-CK (K(m)=0.2 microM) at seryl sites which are different from the sites affected by casein kinase-2 (CK2) in the same protein. A study with peptide substrates would indicate that the G-CK sites in GRP94 conform to the motif S-R/K-E-X (X being different from D and E) which is not recognized by CK2.
authors.affiliation: Dipartimento di Chimica Biologica, Centro per lo Studio delle Biomembrane del CNR and CRIBI, University of Padova, Viale G. Colombo 3, 35121, Padua, Italy.
authors.forename: A M
authors.initials: AM
authors.lastname: Brunati
authors.forename: A
authors.initials: A
authors.lastname: Contri
authors.forename: M
authors.initials: M
authors.lastname: Muenchbach
authors.forename: P
authors.initials: P
authors.lastname: James
authors.forename: O
authors.initials: O
authors.lastname: Marin
authors.forename: L A
authors.initials: LA
authors.lastname: Pinna
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D047390:Casein Kinase II; D047388:Casein Kinases; D005260:Female; D006056:Golgi Apparatus / Q000201:enzymology*; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D007774:Lactation; D008321:Mammary Glands, Animal / Q000201:enzymology / Q000378:metabolism*; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008862:Microsomes, Liver; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D013379:Substrate Specificity
chemical_list: D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; C018551:glucose-regulated proteins; D010768:Phosphoserine; D011494:Protein Kinases; D047390:Casein Kinase II; D047388:Casein Kinases; D017346:Protein Serine-Threonine Kinases