title: AKAP5 and AKAP12 Form Homo-oligomers.
abstract: BACKGROUND
  A-kinase-anchoring proteins, AKAPs, constitute a family of scaffolds that play an essential role in catalyzing the spatial-temporal, dynamic interactions of protein kinase A, protein kinase C, tyrosine kinases, G-protein-coupled receptors and ion channels. We studied AKAP5 (AKAP79; MW ~47 kDa) and AKAP12 (gravin, SSECKS; MW ~191 kDa) to probe if these AKAP scaffolds oligomerize.
  
  
  RESULTS
  In gel analysis and sodium-dodecyl sulfate denaturation, AKAP12 behaved with a MW of a homo-dimer. Only in the presence of the chaotropic agent 8 M urea did gel analysis reveal a monomeric form of AKAP12. By separation by steric-exclusion chromatography, AKAP12 migrates with MW of ~840 kDa, suggestive of higher-order complexes such as a tetramer. Interestingly, the N-(1-840) and C-(840-1782) terminal regions of AKAP12 themselves retained the ability to form dimers, suggesting that the structural basis for the dimerization is not restricted to a single "domain" found within the molecule. In either sodium dodecyl sulfate or urea, AKAP5 displayed a relative mobility of a monomer, but by co-immunoprecipitation in native state was shown to oligomerize. When subjected to steric-exclusion chromatography, AKAP5 forms higher-order complexes with MW ~220 kDa, suggestive of tetrameric assemblies.
  
  
  CONCLUSIONS
  Both AKAP5 and AKAP12 display the capacity to form supermolecular homo-oligomeric structures that likely influence the localization and function of these molecular scaffolds.
authors.affiliation: Departments of Pharmacology, Heath Sciences Center, School of Medicine, State Univerdity of New York at Stony Brook, NY 11794-8651 USA. gao@pharm.stonybrook.edu.
authors.forename: Shujuan
authors.initials: S
authors.lastname: Gao
authors.forename: Hsien-Yu
authors.initials: HY
authors.lastname: Wang
authors.forename: Craig C
authors.initials: CC
authors.lastname: Malbon