PLANT CYCLINS - A UNIFIED NOMENCLATURE FOR PLANT A-TYPE, B-TYPE AND D-TYPE CYCLINS BASED ON SEQUENCE ORGANIZATION

The comparative analysis of a large number of plant cyclins of the A/B family has recently revealed that plants possess two distinct B-type groups and three distinct A-type groups of cyclins [1]. Despite earlie r uncertainties, this large-scale comparative analysis has allowed an unequivocal definition of plant cyclins into either A or B classes. We present here the most important results obtained in this study, and e xtend them to the case of plant D-type cyclins, in which three groups are identified. For each of the plant cyclin groups, consensus sequenc es have been established and a new, rational, plant-wide naming system is proposed in accordance with the guidelines of the Commission on Pl ant Gene Nomenclature. This nomenclature is based on the animal system indicating cyclin classes by an upper-case roman letter, and distinct groups within these classes by an arabic numeral suffix. The naming o f plant cyclin classes is chosen to indicate homology to their closest animal class. The revised nomenclature of all described plant cyclins is presented, with their classification into groups CycA1, CycA2, Cyc A3, CycB1, CycB2, CycD1, CycD2 and CycD3.