AN EXON-TRAPPING SYSTEM WITH A NEWLY CONSTRUCTED TRAPPING VECTOR PEXT2 - ITS APPLICATION TO THE PROXIMAL REGION OF THE HUMAN CHROMOSOME-21 LONG ARM

We have developed an exon-trapping system with a newly constructed tra pping vector containing multiple cloning sites (designated pEXT2). The system revealed high sensitivity for trapping a control exon from sev eral hundred kbp of DNA. We have applied the system to the cosmid clon es located on human chromosome 21p11-q21, and identified two fragments highly homologous to neurofibromatosis 1 (NF1) gene and a clearly tra nscribed fragment hybridized with approximately 1.6 kb RNA from human brain and human glioblastoma A172 cell.