Antitrypsin Siiyama is a rare example of the deficiency variants of antitrypsin that accumulate
in the endoplasmic reticulum of the hepatocyte. The common example is Z antitrypsin, which
has a mutation (Glu342–> Lys) at the junction of the head of the fifth strand of the A sheet
and the base of the reactive center loop. It was previously shown that Z antitrypsin
spontaneously polymerizes due to the insertion of the reactive center loop of one molecule
into the A sheet of a second. The mutation in antitrypsin Siiyama (Ser53–> Phe) affects a …