Association of Krev-1/rap1a with Krit1, a novel ankyrin repeat-containing protein encoded by a gene mapping to 7q21-22.
Krev-1/rap1A is an evolutionarily conserved Ras-family GTPase whose cellular function remains unclear, but which has been proposed to function as a tumor suppressor gene, and may act as a Ras antagonist. To elucidate Krev-1 activity, we have used LexA-Krev-1 in a two-hybrid screen of a HeLa cell cDNA library. Of the two cDNA classes isolated, one contained a single isolate encoding the known Krev-1 interactor Raf, while the second contained multiple isolates coding for a previously undescribed protein which we have designated Kritl (for Krev Interaction Trapped 1). The full length Krit1 cDNA encodes a protein of 529 amino acids, with an amino-terminal ankyrin repeat domain and a novel carboxy-terminal domain required for association with Krit1. Krit1 interacted strongly with Krev-1 but only weakly with Ras, suggesting it might specifically regulate Krev-1 activities. Krit1 mRNA and protein are expressed endogenously at low levels, with tissue specific variation. Intriguingly, the Krit cDNA has been mapped by FISH to chromosome 7q21-22, a region known to be frequently deleted or amplified in multiple forms of cancer.
Serebriiskii
I
I
Division of Basic Sciences, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
Estojak
J
J
Sonoda
G
G
Testa
J R
JR
Golemis
E A
EA
D000595:Amino Acid Sequence; D017089:Ankyrin Repeat; D001483:Base Sequence; D002874:Chromosome Mapping; D002897:Chromosomes, Human, Pair 7; D003001:Cloning, Molecular; D019204:GTP-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D000075927:KRIT1 Protein; D008869:Microtubule-Associated Proteins; D008969:Molecular Sequence Data; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D020668:rap GTP-Binding Proteins
D000075927:KRIT1 Protein; C107928:KRIT1 protein, human; D008869:Microtubule-Associated Proteins; D011518:Proto-Oncogene Proteins; D019204:GTP-Binding Proteins; D020668:rap GTP-Binding Proteins