Cyclin is a component of the sea urchin egg M-phase specific histone H1 kinase.

Abstract

A so‐called ‘growth‐associated’ or ‘M‐phase specific’ histone H1 kinase (H1K) has been described in a wide variety of eukaryotic cell types; p34cdc2 has previously been shown to be a catalytic subunit of this protein kinase. In fertilized sea urchin eggs the activity of H1K oscillates during the cell division cycle and there is a striking temporal correlation between H1K activation and the accumulation of a phosphorylated form of cyclin. H1K activity declines in parallel with proteolytic cyclin destruction of the end of the first cell cycle. By virtue of the high affinity of the fission yeast p13suc1 for the p34cdc2 protein, H1K strongly binds to p13‐Sepharose beads. Cyclin, p34cdc2 and H1K co‐purify on this affinity reagent as well as through several conventional chromatographic procedures. Anticyclin antibodies immunoprecipitate the M‐phase specific H1K in crude extracts or in purified fractions. Sea urchin eggs appear to contain much less cyclin than p34cdc2, suggesting that p34cdc2 may interact with other proteins. These results demonstrate that cyclin and p34cdc2 are major components of the M‐phase specific H1K.

Analysis of cyclin B1 and CDK activity during apoptosis induced by camptothecin treatment

“…Total cell lysate (0.5-1.0 mg) was incubated with antibodies directed against cyclin E1 (13A3, Novocastra, 8 ml), cyclin A2 (H-432, Santa Cruz, 5 ml) or cyclin B1 (GNS1, Santa Cruz, 5 ml) at 41C and complexes were recovered with protein A/G-sepharose beads. The beads were washed three times with bead buffer and twice with Buffer C (60 mM b-glycerophosphate, 15 mM p-nitrophenylphosphate, 25 mM MOPS (pH 7.2), 5 mM EGTA, 15 mM MgCl 2 , 1 mM DTT, 1 mM sodium vanadate, 1 mM phenylphosphate) (Meijer et al, 1989).…”

On cyclins, oocytes, and eggs

“…purified Xenopus MPF to near homogeneity and showed that it is a dimer containing a 34 kd Ser/Thr protein kinase subunit and a 45 kd phosphoprotein. The 34 kd subunit was subsequently identified as cdc2, the Xenopus homolog of the cdc2 ϩ gene product from Schizosaccharomyces pombe (Dunphy et al, 1988;Gautier et al, 1988), and the 45 kd subunit was identified as a B-type cyclin (Draetta et al, 1989;Labbé et al, 1989;Meijer et al, 1989). Purified Xenopus MPF of metaphase II-arrested oocytes contains equivalent amounts of cdc2 complexed with either B1 or B2 cyclin .…”

“…Cyclin B has been reported to be phosphorylated during Xenopus meiotic maturation (Gautier and Maller, 1991), and the appearance of cdc2 kinase activity correlates closely with the phosphorylation of the cyclin B subunit (Meijer et al, 1989). Since purified MPF is known to phosphorylate cyclin B2 in vitro , one kinase that phosphorylates cyclin B in vivo is probably the cdc2 kinase itself, although other kinases such as c-mos product (Roy et al, 1990) or MAP kinase (Izumi and Maller, 1991) may also phosphorylate cyclins B1 and B2.…”

Human cDNAs encoding homologs of the small p34Cdc28/Cdc2-associated protein of Saccharomyces cerevisiae and Schizosaccharomyces pombe.

“…It has been demonstrated in several systems that the active form of Cdc2/Cdc28 protein kinase exists as a multimeric complex with other proteins Draetta et al 1987Arion et al 1988;Draetta and Beach 1988;Gautier et al 1988Gautier et al , 1990Wittenberg and Reed 1988;Labbe et al 1989b;Meijer et al 1989;Pondaven et al 1990). One of the proteins that associates with Cdc2/Cdc28 has been identified as cyclin (Booher et al 1989;Labbe et al 1989b;Meijer et al 1989;Pines and Hunter 1989;Gautier et al 1990).…”