passages.id: split_5_test_238_passage
passages.type: progene_text
passages.text: In fission yeast , two distinct Cdc4p - related proteins , Pop1p / Ste16p [ 10 ] [ 11 ] and the recently identified Sud1p / Pop2p [ 12 ] , regulate the stability of the replication initiator Cdc18p and the Cdk inhibitor Rum1p .