Alk1 and Alk2 are two new cell cycle-regulated haspin-like proteins in budding yeast.
Haspin is a protein kinase identified in mouse and human cells, and genes coding for haspin-like proteins are present in virtually all eukaryotic genomes sequenced so far. Two haspin homologues, called Alk1 and Alk2, are present in the yeast Saccharomyces cerevisiae. Both Alk1 and Alk2 exhibit a weak auto-kinase activity in vitro, are phosphoproteins in vivo and are hyperphosphorylated in response to DNA damage. The amount and modification of the two proteins is greatly regulated during the cell cycle. In fact, Alk1 and Alk2 levels peak in mitosis and late-S/G2, respectively, and phosphorylation of both proteins is maximal in mitosis. Control of protein stability plays a major role in Alk2 regulation. The half-life of Alk2 is particularly short in G1; mutagenesis and genetic analysis indicate that its degradation is controlled by the APC pathway. Overexpression of ALK2, but not of ALK1, causes a mitotic arrest, which is correlated to the kinase activity of the protein. This finding, together with its cell cycle regulation, suggests a role for Alk2 in the control of mitosis.
Nespoli
Alessandro
A
Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milano, Italy.
Vercillo
Raffaella
R
di Nola
Lisa
L
Diani
Laura
L
Giannattasio
Michele
M
Plevani
Paolo
P
Muzi-Falconi
Marco
M
D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D004271:DNA, Fungal / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008938:Mitosis; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
D018797:Cell Cycle Proteins; D004271:DNA, Fungal; C530657:Haspin protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C515738:Alk1 protein, S cerevisiae; C515739:Alk2 protein, S cerevisiae; C530656:HASPIN protein, human; D017346:Protein Serine-Threonine Kinases