Abstract: A novel conserved amino acid motif ("PAS") which provides a binding site for homo and hetero protein interactions has been found in mammalian and insect proteins. Abnormalities in these protein interactions are believed to be responsible for a variety of human diseases or conditions, including behavioral disorders and epithelial tissue cancers. Methods for identifying persons who have a disposition towards these behavioral disorders or epithelial tissue cancers are described. Methods are also described for identifying agonists and antagonists of proteins or related peptides containing PAS domains. Screening such agents involves assessing the ability of candidate compounds to promote or interfere with the binding of certain biologic preparations comprised of PAS-containing proteins. Successful agonists or antagonists should be useful in modifying the effects of human behavioral disorders, as well as certain epithelial cancers.

Abstract: A protein comprising at least a first functional site having the ability to bind the cap structure of mRNA and a second functional site having the ability to bind a solid support matrix in such a manner as to allow the first functional site to be immobilized and still remain functionally accessible to interact with the cap structure of mRNA. Also within the scope of the present invention is a method for generating a cDNA library mostly containing full-length cDNAs. The method comprises the incubation of a mixture comprising mRNA:cDNA hybrids with 1) a single strand RNA specific nuclease and 2) the above-mentioned protein. The resulting mixture is then passed through a column comprising a support matrix having the ability to bind the second functional site of the above-mentioned protein in order to selectively bind complete mRNA:cDNA hybrids. The mRNA:cDNA hybrids are then competitively eluted with a cap analog and full-length cDNA strands are separated and recovered.