ISSN:
1432-1424
Keywords:
intestine
;
aminopeptidase N
;
biosynthesis
;
glycoproteins
;
A antigenicity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary A papain treatment at 15°C and pH 7.3 of a microsomal fraction from rabbit enterocytes quantitatively releases the aminopeptidase N integrated in the plasma membranes without solubilizing the enzyme integrated in the intracellular membranes. Working on A+ rabbits, characterized by the presence on the brush-border hydrolases of glycans corresponding to the human blood group A-determinant structure, it was possible to separate the intracellular aminopeptidase into two major molecular forms with or without these determinants. The molecular form devoid of human blood group A antigenicity corresponds to the only stable intermediate of glycosylation, bearing N-linked high mannose oligosaccharides. This endoglycosidase H-sensitive form is fully active and represents in the steady state about 1% of the total cellular aminopeptidase. It contains a cytoplasmic sequence of about 3000 daltons that has not yet been detected in the mature form. The A antigenicity is acquired simultaneously with processing of high mannose glycans to complex glycans. Pulse chase labeling of jejunum loops with [35S]-methionine showed that the complete processing of the transient form synthesized during 10 min takes 1 hr. During the last 30 min of processing, all the newly transformed molecules are transported to the plasma membrane.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01868745
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