Sib selection.

Isolation of a particular clone from a library by sib selection is based on fractionating the library and choosing a positive subfraction which is consequently enriched for the clone of interest. The goal is to repeat this cycle until the enrichment process results in purification. As discussed in this chapter, particular patterns of fractionating are more efficient than others depending on the relative abundance of the clone, and the size of the original library. Importantly, sib selection is an isolation process that can be used in conjunction with any assay system. In particular, it may be used to isolate a gene from a library where there is an assay for the gene product, but no selection or sequence information available.