Congenital sucrase-isomaltase deficiency arising from cleavage and secretion of a mutant form of the enzyme
J. Clin. Invest. Ralf Jacob, et al. 106:281 doi:10.1172/JCI9677 [Go to this article.]

Figure 4
Expression of mutant SI cDNA in MDCK cells. (a) MDCK cells were transfected with phSI (wild-type [WT]) and pSG8-SI_T/C (L340P) and biosynthetically labeled with ³⁵S-methionine for 1 hour followed by a chase period for the indicated times. The cell lysates (L) and the culture media (M) were separately immunoprecipitated with mAb anti-SI. Thereafter the immunoprecipitates were divided into equal parts and treated or not treated with Endo H; they were analyzed by SDS-PAGE on 6% slab gels and by fluorography. (b) MDCK cells were transfected with pSG8-SI_T/C, and 48 hours after transfection they were labeled at 15°C with ³⁵S-methionine for 6 hours. Lysis was performed in the presence of TX-114. SI was immunoprecipitated from the aqueous (S) and the detergent (P) phase, treated with Endo H, and analyzed by SDS-PAGE on 6% slab gels followed by fluorography. The additional band appearing in the L340P samples in a and b is indicated by arrowheads.