AlphaB-crystallin phosphorylated at Ser-59 is localized in centrosomes and midbodies during mitosis.
We have reported that the three serine residues in alphaB-crystallin are phosphorylated under various stress conditions. We prepared affinity-purified antibodies recognizing each of the phosphorylated serine residues (Ser-19, Ser-45, and Ser-59, respectively) in alphaB-crystallin with peptides (p19S, p45S, or p59S) that contained the corresponding phosphorylated serine residue. Immunocytochemically anti-p45S antibodies stained the cytoplasm of mitotic cells (J. Biol. Chem. 273, 28,346-28,354). We have now found that the anti-p59S antibodies recognize centrosomes and midbodies of dividing cells. alphaB-Crystallin was the only protein recognized by the anti-p59S antibodies in Western blot analyses of isolated centrosome fractions. alphaB-Crystallin phosphorylated at Ser-59 was localized at the microtubule organizing centers by means of double staining with anti-beta-tubulin antibody in aster formation analysis and was co-localized with gamma-tubulin in centrosomes. Gamma-Tubulin was co-immunoprecipitated with alphaB-crystallin in U373 glioma cell extracts. On the other hand, the location of the phosphorylated alphaB-crystallin deviated from that of alpha-tubulin or gamma-tubulin in the midbody region. Taken together with the evidences that several chaperones are distributed to centrosomes, these results suggest that alphaB-crystallin as a chaperone might be also involved in the quality control of proteins.
Inaguma
Y
Y
Department of Biochemistry, Institute for Developmental Research, Aichi Human Service Center, Japan.
Ito
H
H
Iwamoto
I
I
Saga
S
S
Kato
K
K
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D018385:Centrosome / Q000378:metabolism*; D003459:Crystallins / Q000378:metabolism*; D000939:Epitopes; D006367:HeLa Cells; D006801:Humans; D007120:Immunochemistry; D051379:Mice; D022101:Microtubule-Organizing Center / Q000378:metabolism*; D008938:Mitosis / Q000502:physiology; D010766:Phosphorylation; D012694:Serine / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism
D003459:Crystallins; D000939:Epitopes; D014404:Tubulin; D012694:Serine