Pinocytosis of poly (alpha, beta-(N-2-hydroxyethyl))-DL-aspartamide and a tyramine derivative by rat visceral yolk sacs cultured in vitro. Ability of phenolic residues to enhance the rate of pinocytic capture of a macromolecule.
Incorporation of 20% tyramine residues into its structure greatly increased the rate of pinocytosis of poly(alpha, beta-(N-2-hydroxyethyl))-DL-aspartamide (PHEA) by rat visceral yolk sacs cultured in vitro. Both the parent macromolecule and the tyramine derivative (PHEA-tyramine) were captured by adsorptive pinocytosis, the higher affinity of the derivative for the yolk sac plasma membrane being responsible for its greater rate of capture. Using 125I-labelled PHEA-tyramine, the relationship between substrate concentration and rate of capture was determined, it was also shown that following internalization, the PHEA-tyramine linkage is resistant to intracellular hydrolysis. Fluorescence micrographs were consistent with capture of both substrates being by pinocytosis and illustrated the highly efficient concentration of the tyramine derivative by yolk sac endodermal cells.
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D007700:Kinetics; D008856:Microscopy, Fluorescence; D009924:Organ Culture Techniques; D010455:Peptides / Q000378:metabolism*; D010873:Pinocytosis; D051381:Rats; D015017:Yolk Sac / Q000378:metabolism*
D010455:Peptides; C044870:alpha, beta-poly((2-hydroxyethyl)aspartamide-co-(4-hydroxyphenethyl)aspartamide)