b) Amounts of ATG16L1 in colonic mucosal biopsy specimens. Proteins (15 μg) from rectal mucosal biopsies of Crohn disease patients and normal controls (N) were separated by denaturing SDS-PAGE, transferred onto polyvinylidine fluoride (PVDF) membranes and probed for the presence of ATG16L1 using a specific primary antibody and horseradish peroxidase-coupled secondary antibody. The abundant 68.2-kDa band corresponds to the predicted molecular weight of the isoform encoded by GenBank AY398617 (UniProt accession number Q676U5). This major protein form was used for three-dimensional modeling of the ATG16L1 protein (Fig. 2). The 48.5-kDa band corresponds to GenBank EF079890, which contains exon 9 (harboring rs2241880) in the same reading frame as the major form. 