title: Identification of casein kinase Ialpha interacting protein partners.
abstract: Casein kinase Ialpha (CKIalpha) belongs to a family of serine/threonine protein kinases involved in membrane trafficking, RNA processing, mitotic spindle formation and cell cycle progression. In this report, we identified several CKIalpha interacting proteins including RCC1, high mobility group proteins 1 and 2 (HMG1, HMG2), Erf, centaurin-alpha1, synaptotagmin IX and CPI-17 that were isolated from brain as CKIalpha co-purifying proteins. Actin, importin-alpha(1), importin-beta, PP2Ac, centaurin-alpha1, and HMG1 were identified by affinity chromatography using a peptide column comprising residues 214-233 of CKIalpha. We have previously shown that centaurin-alpha1 represents a CKIalpha partner both in vitro and in vivo. The nuclear protein regulator of chromosome condensation 1 (RCC1) is a guanosine nucleotide exchange factor for Ran which is involved in nuclear transport and mitotic spindle formation. Here we show that CKIalpha and RCC1 interact in brain and in cultured cells. However, the interaction does not involve residues 217-233 of CKIalpha which are proposed from X-ray structures to represent an anchoring site for CKI partners. Formation of the RCC1/CKIalpha complex is consistent with the association of the kinase with mitotic spindles. In conclusion, we have identified a number of novel CKIalpha protein partners and their relations to CKI are discussed.
authors.affiliation: The University of Edinburgh, Division of Biomedical and Clinical Laboratory Sciences, Hugh Robson Building, George Square, Edinburgh, UK. thierry.dubois@curie.fr
authors.forename: Thierry
authors.initials: T
authors.lastname: Dubois
authors.forename: Steven
authors.initials: S
authors.lastname: Howell
authors.forename: Eva
authors.initials: E
authors.lastname: Zemlickova
authors.forename: Alastair
authors.initials: A
authors.lastname: Aitken
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D019556:COS Cells; D047388:Casein Kinases; D018797:Cell Cycle Proteins; D002522:Chlorocebus aethiops; D020662:Guanine Nucleotide Exchange Factors / Q000302:isolation & purification / Q000378:metabolism*; D024243:HMGB1 Protein / Q000378:metabolism; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D010446:Peptide Fragments / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D008941:Spindle Apparatus / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism; D028901:alpha Karyopherins / Q000378:metabolism
chemical_list: D000199:Actins; D018797:Cell Cycle Proteins; D020662:Guanine Nucleotide Exchange Factors; D024243:HMGB1 Protein; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D010446:Peptide Fragments; D014404:Tubulin; D028901:alpha Karyopherins; C087978:karyopherin alpha 2; D011494:Protein Kinases; D047388:Casein Kinases; D010749:Phosphoprotein Phosphatases