LIM domain proteins were demonstrated to play key roles in various biological processes such as embryonic development, cell lineage determination, and cancer differentiation. Actin binding LIM protein 1 (abLIM1) was reported to be localized in a genomic region often deleted in human cancers and suggested to be involved in axon guidance. Recently, existence of a second family member was reported, actin binding LIM protein 2. By means of computational biology and comparative genomics, we now characterized an additional, third member of the actin binding LIM protein subgroup, actin binding LIM protein 3 (abLIM3). The human mRNA sequence was previously annotated as differentially regulated in hepatoblastoma compared to normal livers. Conservation of key structural features of abLIM1 and abLIM2, four LIM domains and a VHD domain, suggested comparable biological function of abLIM3 as a linker between actin cytoskeleton and cell signaling pathways. AbLIM3 was found to be conserved in vertebrates, as orthologous sequences were characterized for mouse, fish, and frog. In addition, we report the existence of abLIM2 orthologs in fish and frog, suggesting a similar degree of evolutionary conservation. The intracellular localization of the abLIM3 protein was predicted to be nuclear by means of Reinhardt's neural network and the k-nearest neighbor algorithm. The corresponding abLIM3 gene was localized to chromosome 5q32 and spanned 119 kb, organized in 24 exons. An RT-PCR based expression profile available from the human unidentified gene-encoded (HUGE) database demonstrated highest expression for abLIM3 in heart, lung, liver, and brain/cerebellum accompanied by lower expression in multiple other tissues. Furthermore, abLIM3 was expressed in fetal liver, CNS, and spinal cord.

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