The Effects of O- and N-Linked Glycosylation on the Secretion and Bile Salt-Stimulation of Pancreatic Carboxyl Ester Lipase Activity

Abstract

Pancreatic carboxyl ester lipase is a glycoprotein that requires millimolar concentrations of trihydroxy bile salts, such as cholate, for maximal catalytic activity against cholesteryl esters and triglycerides. Binding of cholate, with subsequent activation, has been proposed to occur in the carboxy-terminal region of carboxyl ester lipase, which contains multiple sites for O-linked glycosylation (1). To investigate the role of O- and N-linked glycosylation in the secretion of carboxyl ester lipase by cells and its activation by cholate, rat carboxyl ester lipase cDNA was transfected into the mutant chinese hamster ovary cell line, IdID, and the ability of the cells to modify the expressed carboxyl ester lipase by N- and O-linked glycosylation was modulated by using various incubation conditions and metabolic inhibitors. The results showed that, similar to other lipases, maximal secretion of carboxyl ester lipase activity required N-linked glycosylation. In contrast, O-linked glycosylation did not affect the secretion of carboxyl ester lipase activity. In addition, the cholate stimulation of hydrolysis was also independent of O-linked glycosylation.

Influence of the probiotic strain Bacillus cereus var. toyoi on the development of enterobacterial growth and on selected parameters of bacterial metabolism in digesta samples of piglets

“…A major factor in fat digestibility is the presence of conjugated bile acids (I VERSON et al. 1991; M ORLOCK ‐F ITZPATRICK and F ISHER 1995), which are important in emulsification, digestion and absorption of dietary lipids in the small bowel. Some intestinal microorganisms such as Lactobacillus spp.…”

O-Glycosylation of C-terminal Tandem-repeated Sequences Regulates the Secretion of Rat Pancreatic Bile Salt-dependent Lipase

“…Because O-linked glycosylation can influence the rate at which a glycoprotein is secreted (16,40), this would provide a clear explanation as to why the secretion rate of BSDL increased with the cell ability to O-glycosylate in the following rank order: CHO ldlD-6B cells grown under non-permissive conditions Ͻ CHO ldlD-6B cells grown under permissive conditions Ͻ CHO K1-3B cells. We further showed that BSDL secreted by CHO ldlD-6B cells was O-glycosylated; the protein incorporated alkaline-sensitive galactose on C-terminal tandem-repeated sequences and carried out Gal␤1-3GalNAc-O-T/S structures, which were recognized by the PNA lectin.…”

Structure of Bovine Pancreatic Cholesterol Esterase at 1.6 Å: Novel Structural Features Involved in Lipase Activation,

“…Electrophoretic characterization of native CEase shows that the increase in the number of isoelectric forms and average pI relative to those of mutant CEase, and the change in mass-to-charge ratio in native CEase, is due to the presence of the N-linked sugars. Even though the function of the N-linked sugars is not well understood, rat pancreatic CEase lacking the N-linked sugars was secreted at 50% lower levels in Chinese hamster ovary and pancreatoma cells, showing a role for glycosylation in the secretion of the enzyme in vivo (30,31). The N-linked sugars are also implicated in protein folding and the thermal stability of the enzyme (31).…”