Among the many abnormally expressed proteins in ovarian cancer, the prominent 
cancer in women, ID1 (inhibitors of DNA binding protein 1) is a potential one 
among other several targets. Interaction of ID1 with ETS-1 (transcriptional 
activator of p16(INK4a)) suppresses the transcription of p16(INK4a) and causes 
abnormal cell proliferation. A peptide aptamer (ID1/3-PA7) has been designed to 
prevent this interaction and thereby leading to the transcription of p16(INK4a). 
However, the structural basis behind the molecular interaction of ID1 with ETS-1 
(agonist) and ID1/3-PA7 (antagonist) is poorly understood. In order to 
understand this structural recognition and their interaction mechanism, in 
silico methods were used. From this interaction analysis, the residues of ETS-1 
involved in interaction with the p16(INK4a) promoter were found to be targeted 
by ID1. Subsequently, ETS-1 binding residues of ID1 were found to be targeted by 
its aptamer- ID1/3-PA7. These results suggest that both ETS-1 and ID1/3-PA7 
binds at the same region harbored by the residues-H97, D100, R103, D104, L107, 
A144, C145, D149, D150 and C154 of ID1. All these observations correlate with 
the experimental reports, suggesting that the identified residues might play a 
crucial role in promulgating the oncogenic effects of ID1. In silico alanine 
scanning mutagenesis also confirms the role of identified hot spot residues in 
p16(INK4a) regulation. Finally, the molecular dynamic simulation studies reveal 
the prolonged stability of the aforementioned interacting complexes. The 
obtained results throw light on the structure and residues of ID1 involved in 
transcriptional regulation of p16(INK4a).