Integrins are transmembrane cell-surface molecules that act as primary adhesion receptors for the extracellular matrix (ECM) and play critical roles in cell-cell adhesion, cell migration, proliferation, and survival. Integrins undergo tension-dependent conformational transitions correlated with changes in binding affinity. Despite the importance of integrin conformation in ECM binding, pathway of integrin activation remains elusive. Using multiscale molecular dynamics modeling and simulation, we study the conformation changes in wild type and mutant integrins and provide an atomic-scale structural information for integrin intermediates. Our simulation work shows that the integrin's ectodomain moves away from the membrane surface and the transmembrane helices from the two subunits of integrin separate for mutant systems that stabilize open state. We finally extend the scope of this study by applying essential dynamics coarse graining and generating heterogeneious elastic network model from various molecular structures of integrin mutants, proposing a multiscale modeling framework for potential future studies of integrin aggregation and focal-adhesion maturation.