Editing Alpha-1 antitrypsin (section)

== Structure ==
A1AT is a single-chain glycoprotein consisting of 394 amino acids in the mature form and exhibits many [[glycoform]]s. The three N-linked glycosylations sites are mainly equipped with so-called diantennary N-[[glycans]]. However, one particular site shows a considerable amount of heterogeneity since tri- and even tetraantennary N-[[glycans]] can be attached to the [[Asparagine]] 107 ([[UniProtKB]] amino acid nomenclature). These [[glycans]] carry different amounts of negatively charged sialic acids; this causes the heterogeneity observed on normal A1AT when analysed by [[isoelectric focusing]]. Also, the fucosylated triantennary N-glycans were shown to have the [[fucose]] as part of a so-called [[Sialyl Lewis x]] [[epitope]],<ref name=Kolarich_2006>{{cite journal | vauthors = Kolarich D, Weber A, Turecek PL, Schwarz HP, Altmann F | title = Comprehensive glyco-proteomic analysis of human alpha1-antitrypsin and its charge isoforms | journal = Proteomics | volume = 6 | issue = 11 | pages = 3369–80 | date = June 2006 | pmid = 16622833 | doi = 10.1002/pmic.200500751 | s2cid = 25498702 }}</ref> which could confer this [[protein]] particular protein-cell recognition properties. The single [[cysteine]] residue of A1AT in position 256 ([[UniProtKB]] nomenclature) is found to be covalently linked to a free single [[cysteine]] by a [[disulfide bridge]].<ref name=Kolarich_2006/>