PURIFICATION OF THE ADENOMATOUS POLYPOSIS-COLI (APC) GENE-PRODUCT

Mutation of the adenomatous polyposis coli (APC) gene is responsible f or familial adenomatous polyposis and is an etiologic factor for diges tive tract malignancies, Although the APC gene product (APC) is believ ed to play a role in growth suppression of colonocytes, the underlying mechanism is not clear, However, recent evidence does suggest that AP C is a microtubule-associated protein (MAP), and like other MAPs, it c an be phosphorylated, as we have shown, To facilitate studies of APC f unction, we purified the APC protein. To purify the full-length APC pr otein, HCT116 human colon cancer cells were lysed and the particulate fraction from the lysate was extracted with ammonium sulfate followed by Sepharose 4B and DEAE-Sephacel column fractionation and then by suc rose zonal density gradient centrifugation. The final purified APC fra ction was determined to be about 1000-fold enriched in APC, The availa bility of purified APC will be valuable in investigating possible grow th-suppressing mechanisms of APC including specific sites of APC phosp horylation and APC's interaction with other cellular proteins. (C) 199 5 Academic Press, Inc.