Polypyrimidine Tract-Binding ProteinRibonucleoproteinsRNA-Binding ProteinsHeterogeneous-Nuclear RibonucleoproteinsRNA SplicingRNA PrecursorsAlternative SplicingExonsHeterogeneous-Nuclear Ribonucleoprotein Group F-HIntronsBase SequenceMolecular Sequence DataEncephalomyocarditis virusHeLa CellsTropomyosinProtein Binding5' Untranslated RegionsRNA, MessengerBinding SitesNucleic Acid ConformationRibosomesProtein BiosynthesisRNA Splice SitesGene Expression RegulationDNA-Binding ProteinsCell NucleusPyrimidinesCell LineAmino Acid SequenceSpliceosomesNuclear ProteinsHeterogeneous-Nuclear Ribonucleoprotein Group CRibonucleoprotein, U2 Small NuclearMutationLaron SyndromePyrimidine NucleotidesRNA, ViralRegulatory Sequences, Ribonucleic AcidRibonucleoprotein, U1 Small NuclearHeterogeneous-Nuclear Ribonucleoprotein Group A-BPicornaviridaeRNAPolydeoxyribonucleotidesCell Extracts