On November 24th and 25th, IBCH PAS hosted dr Wojciech Galej from the European Molecular Biology Laboratory (EMBL), Grenoble, France. Dr Galej specializes in structural biology and biochemistry and cryo-electron microscopy (cryo-EM). During the lecture, dr Galej presented his recent results concerning the conformation of the spliceosome at the early stages of mRNA splicing. Then, he presented how another complex called integrator engages in premature transcription termination. Both, the spliceosome and the integrator are macromolecular complexes composed of multiple proteins, and in the case of the spliceosome also RNAs, that undergo massive dynamic conformational changes. The technical development of cryo-EM over recent years has enabled visualizing such dynamic states to explain complex cellular processes. The visit also encompassed six scientific meetings with 7 IBCH and other local scientists.