kininogen-1 (kng1), also known as alpha-2-thiol proteinase inhibitor, williams-fitzgerald-flaujeac factor or the hmwk-kallikrein factor is a protein that in humans is encoded by the "kng1" gene. kininogen-1 is the precursor protein to high-molecular-weight kininogen (hmwk), low-molecular-weight kininogen (lmwk), and bradykinin.