NIF3L1 BP1 (Ngg1-interacting factor 3-like 1 binding protein 1), also known as THOC7 (THO complex subunit 7 homolog), fSAP24 or hTREX30, is a 204 amino acid cytoplasmic and nuclear protein that belongs to the THOC7 family and interacts with NIF3L1. NIF3L1 BP1 is a component of the THO/TREX complex that is recruited to transcribed genes and travels along with RNA polymerase II (Pol II) during elongation, coupling Pol II with RNA splicing and export factors. The THO/TREX complex also plays a role in the export of Kaposi's sarcoma-associated herpesvirus (KSHV) intronless mRNAs and infectious virus production. The gene that encodes NIF3L1 BP1 maps to human chromosome 3p14.1.