The domain structure of the kininogens. The kininogens are produced by one gene with 11 exons (E1-E11). E1-E3 codes for domain 1 (D1) on both HK (high molecular weight kininogen) and LK (low molecular weight kininogen). Parts of domain 1 inhibit atrial naturetic factor. E4-E6 codes for domain 2 (D2), which has papain and unique calpain inhibitory sequences. E7-E9 codes for domain 3 (D3), which has papain inhibitory sequences. Domain 4 (D4) is coded by part of E10; it is the bradykinin sequence on kininogens and the first 12 amino acids of the light chains of HK and LK. The remainder of E10 codes for HK's light chain, which consists of domain 5 (D5H ) and domain 6 (D6H ). D5H is an artificial surface binding region; D6H has the prekallikrein and factor XI binding regions. Domains 3, 4, and 5 on HK also participate in cell binding. E11 codes for the remainder of the unique light chain of LK (D5L ).
