 Protein 3D structures are currently determined experimentally through X @-@ ray crystallography or nuclear magnetic resonance ( NMR ) spectroscopy . The process is slow ( it can take weeks or even months to figure out how to crystallize a protein for the first time ) and comes at high cost ( around $ 100 @,@ 000 USD per protein ) . Unfortunately , the rate at which new sequences are discovered far exceeds the rate of structure determination – out of more than 7 @,@ 400 @,@ 000 protein sequences available in the NCBI non @-@ redundant ( nr ) protein database , fewer than 52 @,@ 000 proteins ' 3D structures have been solved and deposited in the Protein Data Bank , the main repository for structural information on proteins . One of the main goals of Rosetta @ home is to predict protein structures with the same accuracy as existing methods , but in a way that requires significantly less time and money . Rosetta @ home also develops methods to determine the structure and docking of membrane proteins ( e.g. , GPCRs ) , which are exceptionally difficult to analyze with traditional techniques like X @-@ ray crystallography and NMR spectroscopy , yet represent the majority of targets for modern drugs . 
