Mo. Rev. Stat. § 386.050

The commission shall consist of five members who shall be appointed by the governor, with the advice and consent of the senate, and one of whom shall be designated by the governor to be chair of the commission. Each commissioner, at the time of the commissioner's appointment and qualification, shall be a resident of the state of Missouri, and shall have resided in the state for a period of at least five years next preceding the appointment and qualification, and shall also be a qualified voter therein and not less than twenty-five years of age. Upon the expiration of each of the terms of office of the first commissioners, the term of office of each commissioner thereafter appointed shall be six years from the time of the commissioner's appointment and qualification and until his successor shall qualify. Vacancies in the commission shall be filled by the governor for the unexpired term.