3.6 Retrieval of IRX4 mutations (Dataset)
The human IRX4 protein contained 253 somatic mutations retrieved from COSMIC database. The database consists of 163 missense, 11 nonsense, 72 coding silent, 3 each insertions and deletion mutations (Figure 7) wherein the DNA binding domain consists of 33 missense mutations, 1 nonsense and 15 coding silent mutations. High number of missense mutations are present in genes that are relevant to a disease phenotype. These mutations generate protein variants with a single amino acid change and are of particular interest in biomedicine73. Given that these single amino acid substitutions have an adverse effect on protein stability and may cause structural changes leading to aberrant binding surfaces and impairing protein function, their functional importance need to be studied using computational approaches before addressing their functional effects. The missense mutations in the homeodomain regions were selected for further predictive analysis. To examine the effect of substitutions on these residues, we performed an extensive comparative analysis of physicochemical properties such as theoretical Isoelectric point (PI), Instability Index (II), Aliphatic Index (AI) for the WT as well as mutant variants using Protparam as detailed in Table 1. The properties primarily PI, molecular weight, AI and extinction coefficient, showed minimal or no change due to the point mutations. However, the Grand Average of Hydropathicity (GRAVY) calculated based on the hydropathy values of each amino acid to the full length of the sequence, indicated a change in hydrophobicity74. Increasing positive scores for some of the mutants showed a greater hydrophobicity of those mutants compared to the native protein. Additionally, II of the protein predicts the stability of the protein in a solution state in a test tube. Out of all the mutants, 15 showed an II of less than 40. The more hydrophobic protein mutants would be difficult to solubilize and are less likely to be resolve on a 2D gel electrophoresis75.