Hepatocyte growth factor rapidly induces the tyrosine phosphorylation of 41-kDa and 43-kDa proteins in mouse keratinocytes.

We have examined the hepatocyte growth factor (HGF)-mediated changes in protein-tyrosine phosphorylation in mouse keratinocytes (PAM-212) and canine kidney epithelial cells (MDCK). In PAM-212 cells HGF and epidermal growth factor, both of which stimulated the DNA synthesis, rapidly induced the tyrosine phosphorylation of two 41-kDa and two 43-kDa proteins: increased tyrosine phosphorylation of those proteins has been commonly observed when quiescent fibroblasts are stimulated with a variety of mitogenic agents. In contrast, HGF did not stimulate the DNA synthesis but induced cell dissociation in MDCK cells; under this condition, increased tyrosine phosphorylation of the 41-kDa and 43-kDa protein was not observed. A possible role of the increased tyrosine phosphorylation of 41-kDa and 43-kDa protein in the signaling pathway of HGF is discussed.     

Sulfated extracellular polysaccharide production by the halophilic cyanobacterium Aphanocapsa halophytia immobilized on light-diffusing optical fibers

 The cyanobacterium, Aphanocapsa halo-phytia MN-11, was immobilized in calcium alginate gel and coated on light-diffusing optical fibers (LDOF) for sulfated extracellular polysaccharide production. Results indicated that sulfated extracellular polysaccharide production depends on the number of immobilized cells and the light intensity. In addition, the production rate reached 116.0 mg (mg dry cells)^-1 day^-1 when the cells that were immobilized on LDOF were incubated under a light intensity of 1380 cd sr m^-2 at a cell concentration of 1.0×10⁸ cells/cm³ gel. Cells immobilized on LDOF produced about ten times more sulfated extracellular polysaccharide than those immobilized in calcium alginate beads only (11.7 mg(mg dry cells)^-1day^-1). Received: 31 March 1995/Revised last revision 12 June 1995/Accepted 26 July 1995     

Enzyme complex structure and location of enzymes in the phthalate degradative pathway in Rhodococcus erythropolis

A. SUEMORI, K. NAKAJIMA, R. KURANE AND Y. NAKAMURA. 1996. Rhodococcus erythropolis strain S1 formed enzymes essential to the degradation of phthalate when grown in phthalate-minimal medium. The reaction responsible for the dihydroxylation of the phthalate-benzene ring was concluded to be catalysed by membrane-associated phthalate 3,4-dioxygenase (PO). Of the other enzymes involved, 3,4-dihydro-3,4-dihydroxyphthalate 3,4-dehydrogenase (PH) and 3,4-dihydroxyphthalate 2-decarboxylase (PC) appeared likely to be membrane-bound, while protocatechuate 3,4-dioxygenase appeared to be present in the cytoplasm. Based on the data, the membrane-bound PO and PH apparently form an enzyme complex, which is associated with the NADH-regenerating system.