cyclin, n. Biochem.
(ˈsaɪklɪn)
[f. cycle n. or v. + -in1.]
1. A protein found in cell nuclei, in amounts which fluctuate during the cell cycle, being greatest during DNA replication. Now called proliferating cell nuclear antigen (PCNA).
| 1981 R. Bravo et al. in Exper. Cell Res. CXXXVI. 319/1 To avoid confusion between the different numbering systems we have termed the nuclear acidic polypeptide ‘cyclin’. 1984 Nature 24 May 376/1 We suggest that the name PCNA be used in future, as it is the earlier nomenclature and the term cyclin has recently become ambiguous. 1989 Proc. Nat. Acad. Sci. LXXXVI. 3189/1 Proliferating-cell nuclear antigen (PCNA; also called cyclin) was originally described in proliferating mammalian cells as a nuclear protein. |
2. Any of a class of structurally similar proteins that are synthesized and destroyed at different points in the cell cycle and are instrumental in the control of DNA replication and division in eukaryotes.
| 1983 T. Evans et al. in Cell XXXIII. 389/1 Oocytes of the surf clam Spisula solidissima also contain proteins that only start to be made after fertilization and are destroyed at certain points in the cell division cycle. We propose to call these proteins the cyclins. 1985 Biol. Bull. CLXIX. 545 The Cyclin A protein which is encoded by a maternally stored mRNA was also studied. 1986 Cell XLVII. 870/1 What is the relationship between cyclin A and cyclin B, a related but distinctly different protein whose levels also oscillate in phase with the mitotic cell cycle? 1991 EMBO Jrnl. IX. 2865/2 Cyclin B has been isolated from a wide variety of organisms that include yeast, sea urchin, starfish, clam, frog, fly and man. 1992 Trends Cell Biol. II. 77/1 Cyclins have come to occupy a central position in our understanding of the regulatory processes that coordinate the cell cycle. |