passages.id: split_4_validation_1198_passage
passages.type: progene_text
passages.text: Three mutations , D399K , D399A , and a deletion mutation that removes residues 393 - 402 , all decrease both the V ( max ) of the actin - activated MgATPase by 8 - 10 - fold and the rate of in vitro motility by a factor of 2 - 3 .