Figure 1: Domain architecture for dystrophin and its isoforms. (A) The schematic representation of transcription initiation sites for full length dystrophin (Dp427m/c/p) and its isoforms (Dp260, Dp140, Dp116 and Dp71) mapped in DMD gene. Here m/c/p stands for muscle, brain or purkinje promoter that decides the tissue specific expression of Dp full length. Molecular weight for each isoforms has been denoted by the corresponding number like Dp427 for 427 kDa protein. Transcription promoter sites have been marked with brown arrows. Green dot marks the position of exon 2 from where full length Dp is being transcribed. Exon 30, 45, 56 and 63 produce isoform Dp260, Dp140, Dp 116 and Dp71 respectively. (B) The domain organization of Dp full length protein and its isoforms and their tissue specific expressions. In full length Dp i.e. Dp427 ABD comprises amino acid 1-246 residues and is followed by its 24-SpR (Spectrin like repeats) which spans 339-3040 amino acid residues. It is interspaced by hinge regions. CRD harbors WW domain (greenfilled box) EF hands and ZZ domain (marked with brown filled box). This domain is comprised of 3055-3360 amino acid residues and the WW domain along with EF hands and ZZ domain is responsible for interaction with β-DG. C TER (C terminal region) is a coiled coiled structure spanning amino acid residues 3361-3865. Majority of the isoforms lack ABD. Dp71 lacks a putative WW domain. Tissue specificity for each isoforms has also been given accordingly.