Iowa Code § 489.1109

A member or other person shall not make a voluntary assignment of an interest in a professional limited liability company to any person, except to the professional limited liability company or to an individual who is licensed to practice in this state a profession which the limited liability company is authorized to practice. The certificate of organization or operating agreement of the professional limited liability company may contain any additional provisions restricting the assignment of interests. Unless the certificate of organization or an operating agreement otherwise provides, a voluntary assignment requires the unanimous consent of the members.