Role of fructose 2,6-bisphosphate in mammary gland of fed, starved and re-fed lactating rats.
The fructose 2,6-bisphosphate (Fru-2,6-P2) content and intracellular concentration of lactating mammary gland was measured in fed, starved and re-fed rats. There was little or no change on starvation, and about 1.5-fold rise on re-feeding, contrasting with estimated glycolytic changes of about 10-fold. The 6-phosphofructokinase (PFK-1) activity of mammary extracts was highly sensitive to added Fru-2,6-P2 under all conditions examined, and appeared to approach saturation at physiological concentrations of this effector. The activity of mammary PFK-1 measured under optimal and 'physiological' conditions suggested that this enzyme operates in vivo at about 24% of maximal rate, and is likely to be an important rate-limiting factor in mammary glycolysis.
D000818:Animals; D005260:Female; D005502:Food; D005635:Fructosediphosphates / Q000378:metabolism*; D006598:Hexosediphosphates / Q000378:metabolism*; D007774:Lactation; D008321:Mammary Glands, Animal / Q000378:metabolism*; D010732:Phosphofructokinase-1 / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D013217:Starvation / Q000378:metabolism
D005635:Fructosediphosphates; D006598:Hexosediphosphates; C027652:fructose 2,6-diphosphate; D010732:Phosphofructokinase-1