Kim, DM Yang, K Yang, BS 2024-01-21T08:07:01Z 2024-01-21T08:07:01Z 2022-01-25 2003-10 1226-3613 https://pubs.kist.re.kr/handle/201004/138155 CDK2 and CDK4 known promoter of cell cycling catalyze phosphorylation of RB protein. Enzyme specificity between two CDKs that work at a different cell cycle phase is not clearly understood. In order to define kinase properties of CDK2 and CDK4 in complex with cycline A or cycline 131 in relation to their respective role in cell cycling regulation, we examined enzymatic properties of both CDK4/cycline D1 and CDK2/cycline A in vitro. Association constant, Km for ATP in CDK4/cyclin D1 was found as 418 muM, a value unusually high whereas CDK2/cyclin A was 23 muM, a value close to most of other regulatory protein kinases. Turnover value for both CDK4/cyclin D1 and CDK2/cyclin A were estimated as 3.4 and 3.9 min(-1) respectively. Kinetic efficiency estimation indicates far over one order magnitude less efficiency for CDK4/cyclin D1 than the value of CDK2/cycline A (9.3 pM(-1) min(-1) and 170 pM(-1) min(-1) respectively). In addition, inhibition of cellular CDK4 caused increase of cellular levels of ATP, even though inhibition of CDK2 did not change it noticeably. These data suggest cellular CDK4/ cyclin D1 activity is tightly associated with cellular ATP concentration. Also, analysis of phosphorylated serine/threonine sites on RB catalyzed by CDK4/ cyclin D1 and CDK2/cyclin A showed significant differences in their preference of phosphorylation sites in RB C-terminal domain. Since RB is known to regulate various cellular proteins by binding and this binding is controlled by its phosphorylation, these data shown here clearly indicate significant difference in their biochemical properties between CDK4/cyclin D1 and CDK2/cyclin A affecting regulation of cellular RB function. English KOREAN SOC MED BIOCHEMISTRY MOLECULAR BIOLOGY Biochemical characterizations reveal different properties between CDK4/cyclin d1 and CDK2/cyclin a Article 10.1038/emm.2003.55 1 EXPERIMENTAL AND MOLECULAR MEDICINE, v.35, no.5, pp.421 - 430 EXPERIMENTAL AND MOLECULAR MEDICINE 35 5 421 430 N scie scopus kci ART000860279 000186884600012 2-s2.0-0344873706 Biochemistry & Molecular Biology Medicine, Research & Experimental Biochemistry & Molecular Biology Research & Experimental Medicine Article CYCLIN-DEPENDENT-KINASE CELL-CYCLE RETINOBLASTOMA PROTEIN SUPPRESSOR GENE G1 PHASE IN-VIVO CANCER PROGRESSION ACTIVATION INHIBITOR CDK2/cyclin A CDK4/cyclin D1 cell cycle Km for ATP p16 RB phosphorylation site