Complex of recombinant human CDK7, Cyclin H1 and MNAT1, full length, with N-terminal His-tags (CDK7 and MNAT1) and C-terminal His-tag (CyclinH1) , (GenBank Accession Nos. NM_001799, NM_001239, and NM_002431 respectively), co-expressed in Sf9 insect cells via a baculovirus expression system.