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A 100-kDa protein was found to be a major cell wall protein in Saccharomyces cereviJiae cells cultured without shaking, but was not present in cells cultured with shaking. The amino acid sequence of this protein was identical to the sequence of Tirlp/Srplp. TlRllSRPl has previously been identified as a gene induced by glucose, cold shock or anaerobiosis and was believed to be a cell membrane protein but not a cell wall protein. However, we found that P-l,3-glucanase solubilized Tirlp/Srplp from the cell wall and the purified Tirlp/Srplp reacted with antiserum to P-1,6-glucan and contained glucose. These results suggest that Tirlp/Srplp is a major structural cell wall protein in the static-cultured yeast cells and is bound to the cell wall through p-1,6-glucan. TIRIISRPl mRNA was transcribed only in the static culture and its transcription was regulated by the ROXl repressor.Keywords: TlRl ; SRPl ; yeast cell wall protein; anaerobic conditions; Rarobacter faecitabidus protease I.Saccharomyces cerevisiae has a rigid cell wall outside its cell membrane [ l , 21. When observed under the electron microscope, the cell wall appears as a layered structure, exhibiting a fibrillar or brush-like outer layer, very rich in mannoproteins, and a transparent and amorphous inner layer, which is mainly composed of glucan [3]. This cell wall is considered to have several functions. It protects the cells from mechanical injury, hypotonic lysis and damaging extracellular enzymes. It also contains many hydrolytic enzymes to facilitate assimilation of nutrients. Another important function of the cell wall is to attach cells to other cells. This attachment is observed in sexual agglutination [4, 51, flocculation [6] and pathogenic attachment to host cells [7].The composition of the cell wall is mainly P-glucan and mannoproteins [I, 21. Chitin is a minor component and is found mostly in bud scars. P-Glucan is comprised of P-1,3-glucan and /l-1,6-glucan. These two types of p-glucan are synthesized by completely different pathways. Mannoproteins are glycoproteins with 0-linked oligomannoses andor N-linked high-mannosetype oligosaccharides having a highly branched outer chain of mannose. Mannoproteins in the yeast cell wall are grouped into two classes [l]. One class is comprised of proteins that are extracted with SDS. These proteins are considered to be non-covalently entrapped in the cell wall. The other class is proteins that are not extracted with SDS [8-lo]. These proteins contain structural cell wall proteins and are covalently bound to the cell wall glucan. They can be solubilized by incubation with /l-1,3-glucanase, which digests the insoluble glucan network [ l l ] or with yeast-lytic protease, which digests mannoproteins [ 121.Because of difficulties in purification and characterization of structural cell wall proteins, only Cwplp, Cwp2p and Tiplp [13, 141 have so far been identified from extracts of the cell walls In previous reports [13, 151, cell wall proteins were prepared from cells grown aerobically with shaking. However...

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The crude venom (protein concentration 9640ƒÊg/ml) was extracted with buffered saline from the spines of the crown-of-thorns starfish Acanthaster planci and assayed for some biological

Therapeutic strategies for leukemia are directed to induction of differentiation and apoptosis as well as growth inhibition. One of the key antileukemic agents, 1-beta-D-arabinofuranosylcytosine (ara C), is clinically applied according to these therapeutic aims. However, the molecular effects of 0.1 microg/ml of ara C, a concentration that corresponds to the serum level in leukemic patients on a conventional dose of ara C, have not been well disclosed. Here, we addressed these issues using K562 cells which derived from a blastic crisis of chronic myeloid leukemia. DNA synthesis of treated cells was suppressed from 1-6 h. But, it recovered at 12 h and no further inhibition was observed. The number of cells was not decreased but DNA fragmentation was observed at 72 h. The number of erythroid-differentiated cells also increased to 30% at 72 h. Along with treatment, no marked alteration of mRNAs for cell cycle-regulating genes was found and the retinoblastoma gene product remained hyperphosphorylated throughout treatment. The expression of mRNAs for apoptosis-regulating genes also remained unchanged, except for slight down-regulation of Bax. c-myc protein was not found later than 48 h, and Max mRNA was downregulated. c-jun was immediately induced, followed by the fluctuated expression level along with treatment. These findings suggest that the 0.1 microg/ml ara C changed the proliferation, differentiation and death of K562 cells in a biphasic manner. In the early phase, DNA synthesis was inhibited without altering the expression of cell cycle regulating-genes. In the latter phase, cell death and erythroid- differentiation occurred in accordance with the down-regulation of c-myc.