Biochemical Journal

Research article

A novel partner for D-type cyclins: protein kinase A-anchoring protein AKAP95

Tatjana ARSENIJEVIC, Chantal DEGRAEF, Jacques E. DUMONT, Pierre P. ROGER, Isabelle PIRSON


Using a yeast interaction screen to search for proteins that interact with cyclin D3 in thyroid gland, we identified the cAMP-dependent AKAP95 (protein kinase A-anchoring protein 95). AKAP95 is a scaffolding protein that primarily co-fractionates with the nuclear matrix, whereas a minor fraction associates with chromatin in interphase cells. In co-transfected Chinese-hamster ovary cells, AKAP95 strongly interacted with the three D-type cyclins, but not with CDK4 (cyclin-dependent kinase 4) or with p27kip1. CDK4 displaced the interaction between cyclin D3 and AKAP95, suggesting that AKAP95 could not be the elusive bridging adaptor between D-type cyclins and CDK4 or play a role in the regulation of cyclin D3–CDK4 activity. Interaction between endogenous AKAP95 and cyclin D3 or cyclin D1 was detected in canine thyrocytes, human fibroblasts and NIH-3T3 cells. As both AKAP95 and cyclins D were recently reported to associate with minichromosome maintenance proteins [Eide, Tasken, Carlson, Williams, Jahnsen, Tasken and Collas (2003) J. Biol. Chem. 278, 26750–26756; Gladden and Diehl (2003) J. Biol. Chem. 278, 9754–9760], we hypothesize that the interaction between AKAP95 and D-type cyclins might serve to facilitate the emerging regulatory role of cyclin D–CDK4 in the formation of the prereplication complex at the DNA replication origins.

  • cyclin-dependent kinase 4 (CDK4)
  • cyclin D
  • prereplication complex
  • protein kinase A-anchoring protein 95 (AKAP95)
  • two-hybrid system


  • The nucleotide sequence of dog AKAP95 has been submitted to the DDBJ, EMBL, GenBank® and GSDB Nucleotide Sequence Databases under the accession number AY382602.

  • Abbreviations used: PKA, protein kinase A; AKAP95, PKA-anchoring protein 95; CDK, cyclin-dependent kinase; CHO, Chinese-hamster ovary; CIP/KIP, CDK-interacting protein/kinase-inhibitory protein; DMEM, Dulbecco's modified Eagle's medium; FCS, foetal calf serum; HA, haemagglutinin; MCM, minichromosome maintenance; NLS, nuclear localization signal; pRB, retinoblastoma susceptibility protein; preRC, prereplication complex; TSH, thyroid-stimulating hormone (thyrotropin).