Cell interactions of enkephalin/polypeptide conjugates.
Enkephalin molecules were bound to poly(Lys) (poly-K) or poly(Ala-Lys-Ala-Leu) (poly-A) and their interactions with NG108-15 cells, platelets, erythrocytes and fibroblast cells were investigated. A fluorescent probe, rhodamine, also was bound to the conjugates for monitoring interactions with these cells. Observations by fluorescence microscopy revealed that NG108-15 cells, platelets, and fibroblast cells were labelled by the conjugates, whereas erythrocytes were not. Since polypeptides without enkephalin moieties were only weakly adsorbed on the cells, it was concluded that the enkephalin/polypeptide conjugates were bound specifically to receptors on the cell membrane. Interestingly, when the enkephalin/poly-K conjugate was bound to NG108-15 and fibroblast cells, fluorescent patches appeared on the membrane. Such patch formation was not clearly observed with an enkephalin/rhodamine or enkephalin/poly-A conjugate. In the case of fibroblast cells, the fluorescence converged to a large cluster, which was ultimately internalized. The results suggest that clustering of the receptors in cell membranes is influenced by the carrier polymer presumably due to cross-linking of the receptors and/or the effect of the cationic polypeptides.
Tsukada
M
M
Department of Polymer Chemistry, Kyoto University, Japan.
Sasaki-Yagi
Y
Y
Kimura
S
S
Imanishi
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001792:Blood Platelets / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D002942:Circular Dichroism; D004285:Dogs; D004745:Enkephalins / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism*; D011940:Receptor Aggregation; D011956:Receptors, Cell Surface / Q000378:metabolism; D012235:Rhodamines
D004745:Enkephalins; D010455:Peptides; D011956:Receptors, Cell Surface; D012235:Rhodamines