Insulin-like growth factor-I and transferrin mediate growth and survival of Chinese hamster ovary cells.

The aim of this investigation was to elucidate the roles of insulin-like growth factor-I (IGF-I) and transferrin in the survival and proliferation of Chinese hamster ovary (CHO) cells upon withdrawal of serum. For this purpose, we employed DNA analysis and flow cytometry to compare CHO cell lines expressing either IGF-I alone or IGF-I and transferrin. The ability of cells to cycle and the occurrence of apoptosis were monitored in these cells in serum-free medium. These results indicate that IGF-I alone is able to maintain the viability of CHO cells for an extended length of time in the absence of serum. Transferrin alone does not promote survival or proliferation. Only in the presence of both IGF-I and transferrin do cells survive and proliferate. Therefore, in attached CHO cultures, IGF-I alone does not stimulate cell proliferation but is a requirement for growth in serum-free medium in cooperation with transferrin. We report on the dual role of IGF-I as a survival factor in CHO cells and its interlocking role with transferrin to stimulate cell growth.

The assignment of the 1H nuclear magnetic resonance spectrum of azurin. An investigation of the 1H NMR spectrum of the blue copper protein, azurin, from Pseudomonas aeruginosa, with reference to the previously determined crystal structure.

A detailed assignment of the 1H nuclear magnetic resonance spectrum of azurin has been made. Resonances associated with the single tryptophan residue, all six phenylalanine residues, one of the two tyrosine residues and all four histidine residues, as well as most of the resonances from the ring-current shifted methyl groups have been assigned. These assignments have been used to study the pH dependence of the structure of the protein and binding of analogues of redox-active reagents to the protein.