Two particle-picking procedures for filamentous proteins:SPHIRE-crYOLOfilament mode andSPHIRE-STRIPER

Structure determination of filamentous molecular complexes involves the selection of filaments from cryo-EM micrographs. The automatic selection of helical specimens is particularly difficult, and thus many challenging samples with issues such as contamination or aggregation are still manually picked. Here, two approaches for selecting filamentous complexes are presented: one uses a trained deep neural network to identify the filaments and is integrated inSPHIRE-crYOLO, while the other, calledSPHIRE-STRIPER, is based on a classical line-detection approach. The advantage of thecrYOLO-based procedure is that it performs accurately on very challenging data sets and selects filaments with high accuracy. AlthoughSTRIPERis less precise, the user benefits from less intervention, since in contrast tocrYOLO,STRIPERdoes not require training. The performance of both procedures on Tobacco mosaic virus and filamentous F-actin data sets is described to demonstrate the robustness of each method.