CHARACTERIZATION AND MAPPING OF 3 NEW MAMMALIAN ATP-BINDING TRANSPORTER GENES FROM AN EST DATABASE

Analysis of the human expressed sequence tag (EST) database identified four clones that contain sequences of previously uncharacterized gene s, members of the ATP-binding cassette (ABC) superfamily. Two new ABC genes (EST20237, 31252) are located at Chromosome (Chr) 1q42 and 1q25 respectively in humans, as determined by FISH; at locations distinct f rom previously mapped genes of this superfamily. Two additional clones , EST 600 and EST 1596, were found to represent different ATP-binding domains of the same gene, ABC2. This gene was localized to 9q34 in hum ans by FISH and to the proximal region of Chr 2 in mice by linkage ana lysis. All genes display extensive diversity in sequence and expressio n pattern. We present several approaches to characterizing EST clones and demonstrate that the analysis of EST clones from different tissues is a powerful approach to identify new members of important gene fami lies. Some drawbacks of using EST databases, including chimerism of cD NA clones, are discussed.