Demonstration of respiratory pigments in clonal insulin-producing beta-cells

The amounts of cytochromes and flavoproteins in insulin-producing RINm5F-cells were investigated with dual wavelength spectroscopy. The cytochromes a, a3, b and c were present in normal stoichiometric proportions. Whereas each cytochrome occurred in a concentration corresponding to 25-75 mumol/kg protein, the total amount of flavoproteins was equivalent to about 200 mumol/kg protein. In support of the existence of a functional respiratory chain, the cytochromes reacted normally both to additions of oxygen and to the inhibitors antimycin A and amytal.