CHARACTERIZATION, MAPPING AND PARTIAL CDNA SEQUENCE OF THE 57-KD INTRACELLULAR KI-1 ANTIGEN

A novel antigen was identified by the cross-reactivity of the anti-CD3 0 antibody Ki-1. This 57-kD intracellular Ki-1 antigen (Ki-1/57) is in duced upon activation of leukocytes and is transported to the nuclear compartment. We describe the partial cloning and sequencing of the Ki- 1/57 cDNA from a lambda gt11-cDNA library derived from the Hodgkin-ana logous cell line L540. New monoclonal antibodies were produced against the recombinant Ki-1/57 protein fragment which were used to confirm t hat the Ki-1/57 antigen is associated with kinase activity and is expr essed in a variety of tumor cell lines and in activated but not restin g leukocytes. The Ki-1/57 gene was mapped to the bands 9q22.3-31 of hu man chromosome 9. This is an area which appears to be associated with secondary chromosomal aberrations in acute myeloid leukemias.