Isolation of a Partial eDNA Clone for RCK. Recombinant clones

We previously demonstrated that the 11q23 breakpoint region, des ignated the RCK locus, of the RC-K8 B-lymphoma cell line with t(l 1;14@q23;q32)is centromeric to PBGD, while breakpoints of infan tile leukemia cell lines with t(l1;19Xq23;p13) are detectable by pulsed field gel electrophoresis with the CD3D probe. In the present study, using a probe within 1.0 kilobase ofthe t(11;14) breakpoint, we isolated a partial complementary DNA clone for the putative RCK gene, which detects a 7.5-kilobase mRNA. Sequence analysis predicted a novelpro tein of 472 amino acids which demonstrated sequence homology to a translation initiation factor/helicase family. We also isolated a phage clonefrom the CD3D/G yeastartificial chromosomeclone(yB22B2) which detects 11and 12-kilobase mRNAs, most likely for the MLL/ ALL-i gene associated t(4;llXq2l;q23) and t(11;19@q23;p13)translo cations. By pulsed-field gel electrophoresis after NotI digestion, this recombinant clone is on a 96-kilobase fragment, while RCK and PBGD probes are on a more telomeric 690-kilobase Nod fragment. These results, altogether, suggested that two different genes, RCK and MLL/ ALL-i, are associated with 11q23 translocations of hematopoietic tu mors.