INTRACELLULAR RECEPTORS:“LIGAND-ACTIVATED
 TRANSCRIPTION FACTORS”
HORMONES WITH INTRACELLULAR RECEPTORS ARE HYDROPHOBIC ALLOWING DIFFUSION
ACROSS PLASMA MEMBRANE
HIGHLY VARIABLE
TRANSCRIPTION-ACTIVATION
DOMAIN
HIGHLY CONSERVED  (66 AMINO ACID)
DNA-BINDING DOMAIN CONTAINING
TWO “ZINC FINGERS”
N
C
THIS PROBLEM IS SOLVED BY UTILISING THE
ENERGY OF HORMONE BINDING AT THE CELL
SURFACE TO ALTER CONFORMATION OF
TRANSMEMBRANE PROTEINS AND THEIR
INTERACTIONS WITH INTRACELLULAR
PROTEINS
POLYPEPTIDE HORMONES  ARE
HYDROPHILIC AND CANNOT DIFFUSE
ACROSS THE PLASMA MEMBRANE