The molecular mechanisms that coordinate transcription, processing, mRNP assembly, and mRNA export from the nucleus through nuclear pores into the cytoplasm have been the focus of intense research in recent years. Data demonstrating a tight association between the processes involved in gene expression are considered. The main protein complexes that play a role in mRNA export are described. The complexes are recruited to mRNA at steps preceding the mRNA export. The functions that the complexes perform at particular steps of gene expression are analyzed, and protein complexes responsible for quality control of mRNP discussed.