SCANNING WHOLE CELLS WITH PHAGE-DISPLAY LIBRARIES - IDENTIFICATION OFPEPTIDE LIGANDS THAT MODULATE CELL-FUNCTION

A general strategy has been developed for rapidly identifying peptides that alter cellular function, which has revealed a series of peptides that inhibit platelet aggregation. First whole cells-platelets in thi s case-were used as an affinity matrix to isolate cell-binding phage f rom a phage-display, random-peptide library. In this step 3 x 10(7) di fferent filamentous phage, each encoding and displaying a different ra ndom peptide, were screened as a single pool. Since it is the peptide displayed on the surface of the phage that presumably causes a particu lar phage to bind specifically to a cell, synthetic peptides were then made based on the predicted sequences of the displayed peptides. Beca use the initial affinity selection step had focused attention on a han dful of peptides, each of the 17 synthetic peptides could be individua lly tested in an appropriate functional assay, such as platelet aggreg ation. The majority of the 17 different peptides that we analyzed inhi bited platelet aggregation; these peptides could be grouped into at le ast five different motifs including the expected RGD motif. It is beli eved that this strategy, which requires neither purification nor prior knowledge of a particular target receptor, will prove to be generally useful for identifying peptide ligands that influence cellular functi on. (C) 1994 Wiley-Liss, Inc.