Mutations of the APC gene play a critical role in both sporadic and familial forms of colorectal cancer. The vast majority of these mutations result in the loss of the carboxyl terminus of the protein. To further elucidate the function of APC, we searched for cellular proteins that associate with its carboxyl terminus. One million human cDNA clones were screened with the use of the interaction trap two-hybrid system, and 67 clones were found to have a phenotype suggestive of an APC-interacting protein. Nucleotide sequence analysis revealed that 48 of these clones were derived from a single novel gene named EB1. The association of APC and EB1 proteins was confirmed with in vitro Binding assays. mAbs against EB1 were then produced and used to demonstrate the association of APC and EB1 in vivo. The EB1 gene was predicted to encode a 268-amino acid protein without significant homology to proteins with known function. However, searches of nucleotide databases did identify evidence for at least two related human genes and a yeast homologue. This conservation suggests an essential function for EB1 that might provide clues to the mechanism through which APC suppresses colonic neoplasia.
↵1 This work was supported in part by grants from the Clayton Fund and NIH Grant CA-57345.
↵3 Recipient of an American Cancer Society Faculty Research Award.
↵4 American Cancer Society Research Professor and Investigator of The Howard Hughes Medical Institute.
↵5 To whom requests for reprints should be addressed, at The Johns Hopkins Oncology Center, 424 North Bond Street, Baltimore, MD 21231.
- Received May 12, 1995.
- Accepted June 1, 1995.
- ©1995 American Association for Cancer Research.