Type I Phosphodiesterase in the Isolated, Brush-Border Membrane of Hymenolepis diminuta

1981 ◽  
Vol 67 (5) ◽  
pp. 617 ◽  
Author(s):  
H. R. Gamble ◽  
P. W. Pappas
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Hymenolepis Diminuta ◽  
Type I

Use of saponin in the preparation of brush border from a parasitic flatworm

1981 ◽  
Vol 59 (6) ◽  
pp. 911-917 ◽  
Author(s):  
M. S. Rahman ◽  
D. F. Mettrick ◽  
R. B. Podesta
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Hymenolepis Diminuta ◽  
Parasitic Flatworm ◽  
Basal Plasma Membrane ◽  
Basal Plasma

Saponin treatment in hypotonic or hypertonic fluids, followed by vibration, was used to isolate the brush border membrane from the surface epithelial syncytium of Hymenolepis diminuta. Electron microscopy of the membrane pellets and the parasites indicated that the area of the syncytium sheered by vibration of the parasites was correlated with the areas of the syncytium in which there occurred the greatest amount of osmotically induced swelling: below and adjacent to the brush border in hypotonic incubation, and the infoldings of the basal plasma membrane of the syncytium in hypertonic incubations. Vesiculation of the microvilli occurred in incubations made hypertonic with mannitol.

A comparison of membrane-bound enzymes of the isolated brush border plasma membranes of the cestodes Hymenolepis diminuta and H. microstoma

Parasitology ◽  
1982 ◽  
Vol 84 (2) ◽  
pp. 391-396 ◽  
Author(s):  
P. W. Pappas ◽  
Elizabeth M. Narcisi
Keyword(s):  
Brush Border ◽  
Adenosine Triphosphatase ◽  
Plasma Membranes ◽  
Leucine Aminopeptidase ◽  
Enzymatic Activities ◽  
Hymenolepis Diminuta ◽  
Type I ◽  
Type Ii ◽  
Membrane Bound ◽  
Membrane Bound Enzymes

SUMMARYPreparations of isolated brush border plasma membrane of Hymenolepis diminuta and H. microstoma possess the following enzymatic activities: alkaline phosphohydrolase (E.C. 3.1.3.1); Type I phosphodiesterase (E.C. 3.1.4.1); ribonuclease (E.C. 3.1.4.22); adenosine triphosphatase (E.C. 3.6.1.3); and 5′-nucleotidase (E.C. 3.1.3.5). The following enzymatic activities could not be demonstrated in either membrane preparation: Type II phosphodiesterase (E.C. 3.1.4.18); cyclic adenosine-3′, 5′-monophosphate phosphodiesterase (E.C. 3.1.4.17); leucine aminopeptidase (E.C. 3.4.11.1); maltase (α-glucosidase; E.C. 3.2.1.20); and lactase (β-galactosidase; E.C. 3.2.1.23). These data generally agree with those of previous studies in which similar membrane-bound enzymes were demonstrated in intact (living) worms.

scholarly journals Human meprinbeta: O-linked glycans in the intervening region of the type I membrane protein protect the C-terminal region from proteolytic cleavage and diminish its secretion

2003 ◽  
Vol 369 (3) ◽  
pp. 659-665 ◽  
Author(s):  
Boris LEUENBERGER ◽  
Dagmar HAHN ◽  
Anastassios PISCHITZIS ◽  
Marianne K. HANSEN ◽  
Erwin E. STERCHI
Keyword(s):  
Membrane Protein ◽  
Brush Border ◽  
Culture Medium ◽  
Brush Border Membrane ◽  
Integral Membrane Protein ◽  
Proteolytic Processing ◽  
Type I ◽  
Β Subunit ◽  
Α Subunit ◽  
Small Intestinal

Human meprin (hmeprin; N-benzoyl-l-tyrosyl-p-aminobenzoic acid hydrolase; EC 3.4.24.18) is a member of the astacin family of zinc metalloendopeptidases. The major site of expression is the brush border membrane of small intestinal and kidney epithelial cells. The enzyme is a type I integral membrane protein composed of two distinct subunits, α and β, which are linked by disulphide bridges. The enzyme complex is attached to the plasma membrane only via the β-subunit. The α-subunit is cleaved in the endoplasmic reticulum in a constitutive manner to remove the C-terminal membrane anchor which leads to secretion of the protein. While the β-subunit of hmeprin remains largely attached to the brush-border membrane some proteolytic processing occurs intracellularly as well as at the cell surface and results in the release of this subunit from the cell. In the present paper, we report that the β-subunit bears multiple O-linked sugar residues in the intervening domain. In contrast, the α-subunit does not contain O-linked oligosaccharides. Our results show that the O-linked carbohydrate side chains in hmeprinβ are clustered around a 13 amino acid sequence that contains the main cleavage site for proteolytic processing of the subunit. Prevention of O-glycosylation by specific inhibitors leads to enhanced proteolytic processing and the consequence is an increased release of hmeprinβ into the culture medium.

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