Peptide antibodies: new tools for cell biology.

The process of preparing antibodies against small peptide subsets of larger proteins is now a very routine and effective tool for cell biological investigations. Now that the identification of genes is commonplace, it is imperative to be able to identify, purify, and characterize the products of these genes. Antibodies against synthetic peptides will aid in discovering the elusive functions of these proteins. Over the past 5 years, peptide antibodies have contributed, and they will doubtless continue to contribute, to the identification of functional domains of proteins. Peptide antibodies provide a means for identifying functional domains conserved during the evolution of families of proteins, and for inhibiting specific functions of multifunctional proteins. Domain-specific antibodies have already increased the molecular resolution with which cell biologists can immunologically examine the function of cellular proteins. Finally, many proteins are now known to exist in subtly different forms, either as the products of separate genes or as the result of posttranslational modifications. Peptide antibodies allow molecular cell biologists, for the first time, to design antibodies for the specific assay of altered forms of a protein. Because they are amenable to specific immunolocalization of highly similar species, peptide antibodies can be considered to be subcellular probes of gene expression and posttranslational modification.