Normally, ice crystals grown in solution only exhibit the basal (0001) and prism faces (1010), and appear as round and flat discs.  However, it appears the presence of AFPs exposes other faces.  It now appears the ice surface 2021 is the preferred binding surface, at least for AFP type I.  Through studies on type I AFP, ice and AFP were initially thought to interact through hydrogen bonding (Raymond and DeVries, 1977).  However, when parts of the protein thought to facilitate this hydrogen bonding were mutated, the hypothesized decrease in antifreeze activity was not observed.  Recent data suggest hydrophobic interactions could be the main contributor.  It is difficult to discern the exact mechanism of binding because of the complex water-ice interface.  Currently, attempts to uncover the precise mechanism are being made through use of molecular modelling programs (molecular dynamics or the Monte Carlo method).