Required for efficient export of polyadenylated RNA and spliced mRNA. Acts as component of the THO subcomplex of the TREX complex which is thought to couple mRNA transcription, processing and nuclear export, and which specifically associates with spliced mRNA and not with unspliced pre-mRNA. TREX is recruited to spliced mRNAs by a transcription-independent mechanism, binds to mRNA upstream of the exon-junction complex (EJC) and is recruited in a splicing- and cap-dependent manner to a region near the 5' end of the mRNA where it functions in mRNA export to the cytoplasm via the TAP/NFX1 pathway. The TREX complex is essential for the export of Kaposi's sarcoma-associated herpesvirus (KSHV) intronless mRNAs and infectious virus production. THOC2 (and probably the THO complex) is involved in releasing mRNA from nuclear speckle domains. Required for NXF1 localization to the nuclear rim. Plays a role for proper neuronal development. Component of the THO complex, which is composed of THOC1, THOC2, THOC3, THOC5, THOC6 and THOC7; together with at least ALYREF/THOC4, DDX39B, SARNP/CIP29 and CHTOP, THO forms the transcription/export (TREX) complex which seems to have a dynamic structure involving ATP-dependent remodeling. Interacts with THOC1, POLDIP3 and ZC3H11A. Expressed in the hippocampus and the cerebral cortex. The disease is caused by variants affecting the gene represented in this entry. Belongs to the THOC2 family. Contaminating sequence. Sequence of unknown origin in the N-terminal part. Truncated N-terminus.