Fig. 1.

Synapse-associated protein (SAP) 97 and inwardly rectifying potassium channel (Kir) 2.3 coimmunoprecipitate from sheep atrial membranes. A: the PDZ binding domain of Kir2.3, residue SAI, is found at the extreme COOH-terminal end of the polypeptide. B: SAP97 is a member of the membrane-associated guanylate kinase homolog (MAGUK) family of scaffolding proteins and contains multiple protein-protein interaction domains such as L27, PDZ, and src homology 3 (SH3). GUK, guanylate kinase. C: sheep atrial membrane preparations were incubated with antibody (monoclonal anti-SAP97 or anti-myc as a control), antibody-protein complexes were isolated using protein G-Sepharose, and the resulting preparations were subjected to Western blot analysis with the anti-Kir2.3 antibody.