AIM1, A NOVEL NONLENS MEMBER OF THE BETA-GAMMA-CRYSTALLIN SUPERFAMILY, IS ASSOCIATED WITH THE CONTROL OF TUMORIGENICITY IN HUMAN-MALIGNANT MELANOMA

AIM1 is a novel gene whose expression is associated with the experimen tal reversal of tumorigenicity of human malignant melanoma. The predic ted protein product of the major 4.1-kb transcript shows striking simi larity to the beta gamma-crystallin superfamily, All known members of this superfamily contain two or four characteristic motifs arranged as one or two symmetrical domains, AIM1, in contrast, contains 12 beta g amma motifs, suggesting a 6-domain structure resembling a trimer of be ta- or gamma-crystallin subunits, The structure of the AIM1 gene shows remarkable similarity to beta-crystallin genes, with homologous intro ns delineating equivalent protein structural units, AIM1 is the first mammalian member of the beta gamma superfamily with a primarily non-le ns role, Other parts of the predicted AIM1 protein sequence have weak similarity with filament or actin-binding proteins, AIM1 is a good can didate for the putative suppressor of malignant melanoma on chromosome 6, possibly exerting its effects through interactions with the cytosk eleton.