, ▁of ▁many ▁prote ins ▁that ▁carry ▁out ▁functions ▁within ▁the ▁cell . ▁ ▁To ▁better ▁understand ▁a ▁protein ' s ▁function ▁and ▁aid ▁in ▁rational ▁drug ▁design , ▁scient ists ▁need ▁to ▁know ▁the ▁protein ' s ▁three - dimensional ▁t ert i ary ▁structure . ▁ ▁Prote in ▁ 3 D ▁structures ▁are ▁currently ▁determined ▁experiment ally ▁via ▁X - ray ▁cry stal log raph y ▁or ▁nuclear ▁magnetic ▁reson ance ▁( N MR ) ▁spect ro sc opy . ▁The ▁process ▁is ▁slow ▁( it ▁can ▁take ▁weeks ▁or ▁even ▁months ▁to ▁figure ▁out ▁how ▁to ▁cry st all ize ▁a ▁protein ▁for ▁the ▁first ▁time ) ▁and ▁cost ly ▁( around ▁US $ 1 0 0 , 0 0 0 ▁per ▁protein ). ▁Unfortunately , ▁the ▁rate ▁at ▁which ▁new ▁sequences ▁are ▁discovered ▁far ▁exceed s ▁the ▁rate ▁of ▁structure ▁determ ination ▁– ▁out ▁of ▁more ▁than ▁ 7 , 4 0 0 , 0 0 0 ▁protein ▁sequences ▁available ▁in ▁the ▁National ▁Center ▁for ▁Bi ote chn ology ▁Information ▁( NC BI ) ▁non redu nd ant ▁( nr ) ▁protein ▁database , ▁fewer ▁than ▁ 5 2 , 0 0 0 ▁prote ins ' ▁ 3 D ▁structures ▁have ▁been ▁solved ▁and ▁depos ited ▁in ▁the ▁Prote in ▁Data ▁Bank , ▁the ▁main ▁repository ▁for ▁struct ural ▁information ▁on ▁prote ins . ▁One ▁of ▁the ▁main ▁goals ▁of ▁Ros etta @ home ▁is ▁to ▁predict ▁protein ▁structures ▁with ▁the ▁same ▁accuracy ▁as ▁existing ▁methods , ▁but ▁in