Interaction of [(3)H]gibberellin A 1 with a sub-cellular fraction from lettuce (Lactuca sativa L.) hypocotyls : Requirement for protein synthesis.

The relationship between protein synthesis and the incorporation of [(3)H]gibberellin A1 ([(3)H]GA1) into a 2,000xg pelletable (2KP) fraction from lettuce (Lactuca sativa L.) hypocotyl sections has been investigated. Concentrations of D-2-(4-methyl-2,6-dinitroanilino)-N-methylpropionamide (MDMP) between 10(-7) M and 10(-4) M caused increasing inhibition of growth, 2KP labelling and incorporation of [(14)C]leucine into soluble protein. Growth and 2KP radioactivity were highly correlated (r=0.996). Transfer to MDMP early or late in the course of GA response caused reductions in both growth and incorporation into the 2KP fraction. Exposure to the inhibitor had more effect at 4 h than at 20 h. The proportions of alkali-soluble and insoluble radioactivity in the 2KP fraction were also altered by this treatment. The implications of these findings are discussed.