CacyBP/SIP, a Calcyclin and Siah-1-interacting Protein, Binds EF-hand Proteins of the S100 Family

• Published in: The Journal of biological chemistry Vol. 277; no. 32; pp. 28848 - 28852
• Main Authors: Filipek, Anna, Jastrzebska, Beata, Nowotny, Marcin, Kuznicki, Jacek
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 09.08.2002
• Subjects: Animals; Blotting, Northern; Blotting, Western; Brain - metabolism; Calcium-Binding Proteins - chemistry; Calcium-Binding Proteins - metabolism; Cell Cycle Proteins; Chromatography, Affinity; EF Hand Motifs; Electrophoresis, Polyacrylamide Gel; Histidine - metabolism; Intracellular Signaling Peptides and Proteins; Ligands; Nerve Growth Factors - metabolism; Nuclear Proteins - metabolism; Plasmids - metabolism; Precipitin Tests; Protein Binding; Protein Structure, Tertiary; Rats; S100 Calcium Binding Protein A6; S100 Calcium Binding Protein beta Subunit; S100 Proteins - metabolism; Spectrometry, Fluorescence; Ubiquitin - metabolism; Ubiquitin-Protein Ligases
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M203602200

Recently, a human ortholog of mouse calcyclin (S100A6)-binding protein (CacyBP) called SIP (Siah-1-interacting protein) was shown to be a component of a novel ubiquitinylation pathway regulating β-catenin degradation (Matsuzawa, S., and Reed, J. C. (2001) Mol. Cell 7, 915–926). In murine brain, CacyBP/SIP is expressed at a high level, but S100A6 is expressed at a very low level. Consequently we carried out experiments to determine if CacyBP/SIP binds to other S100 proteins in this tissue. Using CacyBP/SIP affinity chromatography, we found that S100B from the brain extract binds to CacyBP/SIP in a Ca 2+ -dependent manner. Using a nitrocellulose overlay assay with 125 I-CacyBP/SIP and CacyBP/SIP affinity chromatography, we found that this protein binds purified S100A1, S100A6, S100A12, S100B, and S100P but not S100A4, calbindin D 9k , parvalbumin, and calmodulin. The interaction of S100 proteins with CacyBP/SIP occurs via its C-terminal fragment (residues 155–229). Co-immunoprecipitation of CacyBP/SIP with S100B from brain and with S100A6 from Ehrlich ascites tumor cells suggests that these interactions are physiologically relevant and that the ubiquitinylation complex involving CacyBP/SIP might be regulated by S100 proteins.