The catalytic subunit of Saccharomyces cerevisiae casein kinase II (Sc CKII) is encoded by the CKA1 and CKA2 genes, which together are essential for viability. Five independent temperature-sensitive alleles of the CKA2 gene were isolated and used to analyze the function of CKII during the cell cycle. Following a shift to the nonpermissive temperature, cka2 ts strains arrested within a single cell cycle and exhibited a dual arrest phenotype consisting of 50% unbudded and 50% largebudded cells. The unbudded half of the arrested population contained a single nucleus and a single focus of microtubule staining, consistent with arrest in G 1 . Most of the large-budded fraction contained segregated chromatin and an extended spindle, indicative of arrest in anaphase, though a fraction contained an undivided nucleus with a short thick intranuclear spindle, indicative of arrest in G 2 and/or metaphase. Flow cytometry of pheromone-synchronized cells confirmed that CKII is required in G 1 , at a point which must lie at or beyond Start but prior to DNA synthesis. Similar analysis of hydroxyurea-synchronized cells indicated that CKII is not required for completion of previously initiated DNA replication but confirmed that the enzyme is again required for cell cycle progression in G 2 and/or mitosis. These results establish a role for CKII in regulation and/or execution of the eukaryotic cell cycle.Casein kinase II (CKII) 1 is a serine/threonine protein kinase which is ubiquitous among eukaryotic organisms (for review, see Issinger, 1993;Pinna, 1990;Tuazon and Traugh, 1991). The enzyme is composed of a catalytic ␣ and regulatory ␤ subunit that combine to form a native ␣ 2 ␤ 2 holoenzyme which is constitutively active in vitro. How (and indeed whether) the enzyme is regulated in vivo is unknown, though regulation via allosteric effectors (e.g. polyamines), covalent modification, cellular redistribution, and substrate-directed effects have all been proposed. CKII recognizes a Ser of Thr residue followed by a series of acidic residues and phosphorylates a broad and intriguing spectrum of both nuclear and cytoplasmic substrates.Although the physiological role of CKII is not known, several lines of evidence suggest a role for the enzyme in cell prolifer-

Casein kinase II (CKII) of Saccharomyces cerevisiae contains two distinct catalytic subunits, ␣ and ␣, that are encoded by the CKA1 and -2 genes, respectively. We have constructed conditional alleles of the CKA1 gene. In contrast to cka1 cka2 ts strains, which exhibit a defect in both G 1 and G 2 /M cell cycle progression, cka1 ts cka2 strains continue to divide for three cell cycles after a shift to restrictive temperature and then arrest as a mixture of budded and unbudded cells with a spherical morphology. Arrested cells exhibit continued growth, a nonpolarized actin cytoskeleton, delocalized chitin deposition, and a significant fraction of multinucleate cell bodies, confirming the presence of a cell polarity defect in cka1 ts strains. The presence of budded as well as unbudded cells in the arrested population suggests that CKII is required for maintenance rather than establishment of cell polarity, although a role in both processes is also possible. The terminal phenotype of cka1 ts strains bears a strong resemblance to that of orb5 strains of Schizosaccharomyces pombe, which carry a temperature-sensitive CKII catalytic subunit mutation, but the underlying mechanism appears to be different in the two cases. These results establish a requirement for CKII in cell polarity in S. cerevisiae and provide the first evidence for functional specialization of CKA1 and -2.

The distribution of various collagen types was studied in rat fibrosarcoma. Collagens extracted from fibrosarcoma tissue were characterized by the criteria of solubility in NaCl, SDS-PAGE, ion exchange chromatography, CNBr peptide mapping and amino acid analysis. Fibrosarcoma was found to produce excess amount of type V, type I trimer and type III collagens; comparatively, type I collagen and total collagen content were noticed to decrease in fibrosarcoma. We observe that the increase in type V collagen content in fibrosarcoma might be due to the enhanced transcription of type V collagen gene. Increased type I trimer collagen in fibrosarcoma might be attributed to the differential expression of alpha 1(I) and alpha 2(I) gene and might also be due to the expression of a different gene for type I trimer collagen.

Bull seminal plasma contains high levels of beta-glucuronidase. The present study describes the isolation and characterization of beta-glucuronidase, and its role in fertilization. beta-glucuronidase was purified by ion exchange chromatography, saccharolactone-agarose affinity chromatography, and gel filtration. The specific activity of the purified enzyme was 4,414 mumoles/mg protein/min. The purified enzyme showed a single band on 7.5% PAGE. On SDS-PAGE, the enzyme appeared to consist of four identical subunits of M(r) 75,000 each. The apparent Km and Vmax for beta-glucuronidase were 0.4 mM and 5.7 mumol/min using phenolpthalein mono-beta-glucuronic acid as the substrate. beta-glucuronidase appeared to accelerate the cumulus dispersion in vitro.