A ribosomal calmodulin-binding protein from Dictyostelium

• Published in: The Journal of biological chemistry Vol. 266; no. 34; pp. 23091 - 23096
• Main Authors: SONNEMANN, J, BÄUERLE, A, WINCKLER, T, MUTZEL, R
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 05-12-1991
• Subjects: Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Animals; Antibodies - immunology; Binding and carrier proteins; Binding, Competitive; Biological and medical sciences; Calmodulin - metabolism; calmodulin-binding protein; Calmodulin-Binding Proteins - genetics; Calmodulin-Binding Proteins - immunology; Calmodulin-Binding Proteins - isolation & purification; Centrifugation, Density Gradient; cloning; Dictyostelium - chemistry; Dictyostelium discoideum; DNA - isolation & purification; Electrophoresis, Polyacrylamide Gel; Fundamental and applied biological sciences. Psychology; genes; Molecular Sequence Data; predictions; Proteins; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; ribosomal proteins; Ribosomal Proteins - genetics; Ribosomal Proteins - immunology; Ribosomal Proteins - isolation & purification; Ribosomes - chemistry; Sequence Alignment; Dictyostelium discoideum; Protozoa; Binding protein; Ribosome; Complementary DNA; Protein synthesis; Immunoblotting assay; Primary structure; Calmodulin; Mycetozoa
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)54467-7

Using 125I-calmodulin as a probe, we have recently identified specific Ca2+/calmodulin-binding proteins in cell extracts from
the cellular slime mold, Dictyostelium discoideum: a major 22-kDa activity, a soluble 78/80-kDa protein, and several membrane-associated
high Mr proteins (Winckler, T., Dammann, H., and Mutzel, R. (1991) Res. Microbiol. 142, 509-519). cDNA clones for at least
two of these proteins have been isolated by ligand screening of a lambda gt11 prophage expression library. Antibodies directed
against the lacZ-cDNA-encoded fusion protein from one of the clones recognized a single 22-kDa component in D. discoideum
extracts which comigrated with the endogenous 22-kDa calmodulin-binding protein. The cDNA-derived nucleotide sequence predicts
a protein of Mr 21,659 with 56% sequence identity (69% homology) with rat ribosomal protein L19. The endogenous 22-kDa calmodulin-binding
activity was associated with ribosomes. It was found to be an integral constituent of the large ribosomal subunit, since it
cosedimented with 60 S ribosomal subunits in sucrose density gradients in the presence of 0.5 M NH4Cl. Our observations point
to a physiological role for calmodulin in the Ca2+ regulation of eukaryotic protein synthesis. Support for this comes from
recent studies showing inhibition of protein synthesis by calmodulin antagonists in Ehrlich ascites tumor cells (Kumar, R.
V., Panniers, R., Wolfman, A., and Henshaw, E.C. (1991) Eur. J. Biochem. 195, 313-319).