The invention relates to novel polypeptides for transporting molecules across cell membranes and, particularly but not exclusively, biological membranes a conjugate comprising at least one of said polypeptides and at least one selected molecule or agent co-joined or conjugated to said polypeptide for the purpose of transporting said molecule or agent across a cell membrane a method of transporting at least one selected molecule or agent across a cell membrane involving the use of at least one of said polypeptides a therapeutic comprising at least one of said conjugates a combination therapeutic comprising at least one of said conjugates and at least one further therapeutic agent a method of treatment involving the use of at least one of said conjugates or said therapeutics.