13] Selection of genetic agents from random peptide aptamer expression libraries

Abstract

Publisher Summary A new class of dominant agents has been developed to facilitate the analysis of processes in diploid and genetically intractable organisms. These molecules are termed “peptide aptamers” because of their similarity to nucleic acid aptamers. Peptide aptamers are defined as antibody-like recognition agents that consist of conformationally constrained peptides displayed on the surface of scaffold proteins and that are distinguished from peptides of variable sequence displayed that are not constrained at both ends by the scaffold. Peptide aptamers are designed to inhibit cellular processes by interacting with proteins and disrupting their biological functions. Combinatorial libraries of peptide aptamers in principle contain aptamers that bind almost any protein target. Peptide aptamers specific for numerous proteins have been isolated by using the yeast two-hybrid system. The fact that peptide aptamers are typically selected in vivo by two-hybrid methods increases the likelihood that the molecules will function in vivo . In support of this notion, peptide aptamers function as reverse dominant agents in both mammalian cells and Drosophila melanogaster . This chapter describes how to obtain and characterize peptide aptamers for both the reverse and forward analysis of cellular processes.