The F-actin cross-linking and focal adhesion protein filamin A is a ligand and in vivo substrate for protein kinase C alpha

• Published in: The Journal of biological chemistry Vol. 278; no. 26; pp. 23561 - 23569
• Main Authors: Tigges, Ulrich, Koch, Bettina, Wissing, Josef, Jockusch, Brigitte M, Ziegler, Wolfgang H
• Format: Journal Article
• Language: English
• Published: United States 27.06.2003
• Subjects: Actins - metabolism; Binding Sites; Calcium; Contractile Proteins - metabolism; Filamins; Focal Adhesions - chemistry; Humans; Ligands; Microfilament Proteins - metabolism; Phospholipids; Phosphorylation; Protein Binding; Protein Isoforms - metabolism; Protein Kinase C - metabolism; Protein Kinase C-alpha; Signal Transduction; Two-Hybrid System Techniques
• ISSN: 0021-9258
• DOI: 10.1074/jbc.M302302200

Filamin A is an established structural component of cell-matrix adhesion sites. In addition, it serves as a scaffold for the subcellular targeting of different signaling molecules. Protein kinase C (PKC) has been found associated with filamin; however, details about this interaction and its significance for cell-matrix adhesion-dependent signaling have remained elusive. We performed a yeast two-hybrid analysis using protein kinase Calpha as a bait and identified filamin as a direct binding partner. The interaction was confirmed in transfected HeLa cells, and serial truncation fragments of filamin A were employed to identify two binding sites on filamin. In vitro ligand binding assays revealed a Ca2+ and phospholipid-dependent association of the regulatory domain of protein kinase C with these sites. Phosphorylation of filamin was found to be isoform-restricted, leading to phosphate incorporation in the C termini of filamin A and C, but not B. PKC-dependent phosphorylation of filamin was also detected in cells. Our data suggest an intimate interaction between filamin and PKC in cell signaling.