We aimed to construct a full-length cDNA bank from an entire set of human genes and to analyze the function of a protein encoded by each cDNA. To achieve this purpose, a multifunctional phagemid shuttle vector, pKA1, was constructed for preparing a high-quality cDNA library composed of full-length cDNA clones which can be sequenced and expressed in vitro and in mammalian cells without subcloning the cDNA fragment into other vectors. Using this as a vector primer, we have prepared a prototype of the bank composed of full-length cDNAs encoding 236 human proteins whose amino acid sequences are identical or similar to known proteins. Most cDNAs contain a putative cap site sequence, some of which show a pyrimidine-rich conserved sequence exhibiting polymorphism. It was confirmed that the vector permits efficient in vitro translation, expression in mammalian cells and the preparation of nested deletion mutants.