Amino acid sequence and tentative structure for human prepro factor IX Amino acid sequence and tentative structure for human prepro factor IX. The locations of the seven introns (A to G) are shown in the various regions of the protein. The prepro leader sequence is cleaved during protein biosynthesis to give rise to the mature protein with an amino-terminal sequence of Y-N-S-G-. The two peptide bonds cleaved by factor XIa (or factor VIIa) during the activation reaction are shown with small arrows. The three amino acids in the catalytic domain (H221, D349, and S365) that participate in catalysis are circled, while the two potential N-linked carbohydrate attachment sites in the activation peptide are shown with solid diamonds. The amino acids are numbered as follows, starting with the amino-terminal end of the protein: −46 to −1 = prepro leader sequence; +1 to 145 = light chain of factor IXa; 146 to 180 = activation peptide; 181 to 415 = catalytic chain of factor IXa. The single-letter code for amino acids is shown in the legend to Fig. 169-5. β = β-hydroxyaspartic acid. (Modified from Yoshitake et al.13 Used with permission.) Source: Introduction to Hemostasis and the Vitamin K-Dependent Coagulation Factors, The Online Metabolic and Molecular Bases of Inherited Disease Citation: Valle D, Beaudet AL, Vogelstein B, Kinzler KW, Antonarakis SE, Ballabio A, Gibson K, Mitchell G. The Online Metabolic and Molecular Bases of Inherited Disease; 2014 Available at: https://ommbid.mhmedical.com/DownloadImage.aspx?image=/data/Books/971/ch169fg9.png&sec=62649746&BookID=971&ChapterSecID=62649663&imagename= Accessed: November 10, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved