The third LIM domain of Enigma: Enigma was initially characterized in humans as a protein containing three LIM domains at the C-terminus and a PDZ domain at N-terminus. The third LIM domain specifically interacts with the insulin receptor and the second LIM domain interacts with the receptor tyrosine kinase Ret and the adaptor protein APS. Thus Enigma is implicated in signal transduction processes such as mitogenic activity, insulin related actin organization, and glucose metabolism. Enigma is expressed in multiple tissues, such as skeletal muscle, heart, bone, and brain. LIM domains are 50-60 amino acids in size and share two characteristic zinc finger motifs. The two zinc fingers contain eight conserved residues, mostly cysteines and histidines, which coordinately bond to two zinc atoms. LIM domains function as adaptors or scaffolds to support the assembly of multimeric protein complexes.
Comment:The two zinc fingers contain eight conserved residues, mostly cysteines and histidines, which coordinately bond to two zinc atoms. The Zn binding residues of LIM domain are highly conserved.
Jiyao W et al.(2023). "The conserved domain database in 2023.",