The function of TREX in gene expression

In recent years, multiple links between the intranuclear steps of gene expression have been shown. One of the key players in this coupling is the so called TREX complex, which couples transcription and mRNA export. It consists of the heterotetrameric THO complex (consisting of the components Tho2, Hpr1, Mft1, and Thp2), the nuclear mRNA export factors Sub2 and Yra1, the SR-proteins Gbp2 and Hrb1, and Tex1. TREX travels along the transcribed gene with RNA polymerase II, binds the nascent mRNA, and “feeds” it into the mRNA export pathway via its subunits and mRNA export factors Sub2 and Yra1 (Fig. 2). Yra1 then directly binds the mRNA exporter Mex67-Mtr2. Mex67-Mtr2 in turn binds directly to the mRNA as well as to nuclear pore proteins and transports the mRNP through the nuclear pore complex to the cytoplasm.