Amino Acid Sequence; Amino Acids/chemistry; Animals; Arabidopsis/enzymology; Blotting, Northern; Blotting, Southern; Bryopsida/enzymology; Cell Division; Chlamydomonas/enzymology; Cloning, Molecular; DNA, Complementary/metabolism; Gene Library; Introns; Molecular Sequence Data; Multigene Family; Nutritional Requirements; Open Reading Frames; Phosphorylation; Phylogeny; Plant Proteins; Polymerase Chain Reaction; Protein Isoforms; Protein Kinases/biosynthesis; Protein Serine-Threonine Kinases/metabolism; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Time Factors; Up-Regulation