Component of the PAF1 complex which is a multifunctional complex involved in transcription initiation via genetic interactions with TATA-binding proteins, elongation and transcription-coupled histone modification. Component of the PAF1 complex which consists of at least cdc-73, ctr-9, leo-1, pafo-1 and rtfo-1. Nuclear localization depends on PAF1 complex components ctr-9, leo-1 and cdc-73. Expressed in both somatic cells and germ cells from the one-cell stage onwards. RNAi-mediated knock-down is mostly embryonic lethal. Embryogenesis proceeds more slowly, with embryos displaying defects in the positioning and shape of epidermal cells. Leo-1 partly mislocalizes to the cytoplasm, but nuclear localization of rtfo-1 is unaffected. Belongs to the PAF1 family.