Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P02749 (beta2-glycoprotein I)
 836 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The specific binding of digoxigenin-labeled lectins to carbohydrate moieties is used to characterize the carbohydrate chains bound to apolipoprotein H. Our results show that apolipoprotein H is rich in sialic acid linked alpha(2-6) to galactose or N-acetylgalactosamine. Sialic acid is not alpha(2-3)-linked to galactose. Galactose is beta(1-4)-linked to N-acetylglucosamine and beta(1-3)-linked to N-acetylgalactosamine. High-mannose N-glycan chains are barely detectable. After N-glycosidase F treatment the molecular weight is substantially reduced. The main band is 32,500 daltons. Carbohydrate O-linked chains, which are mainly represented by sialic acid, are alpha(2-6)-linked to galactose or N-acetylgalactosamine. Galactose is also organized in O-linked chains and it is beta(1-4)-linked to N-acetylglucosamine and beta(1-3)-linked to acetylgalactosamine. Biochemical analysis of carbohydrate structures reveals that no specific carbohydrate complex is bound to a single isoform.
 ...
PMID:Qualitative analysis of the carbohydrate composition of apolipoprotein H. 915 91

We studied the structure of N-linked carbohydrates bound to apolipoprotein H by a combination of two methods which make use of lectins. Digoxigenin-labelled lectins are used for the structural characterization of carbohydrate chains of glycoproteins. Concanavalin A lectin affinity chromatography was used to analyse apolipoprotein H according to the characteristics of its carbohydrate chain inner to sialic acid residues. Our results from digoxigenin-labelled lectins analysis showed that apolipoprotein H gave positive bands to SNA, DSA, GNA, PNA and AAA lectins. Apolipoprotein H gave a negative band when reacted with MAA lectin. When we applied apolipoprotein H onto the Concanavalin A lectin column no detectable amounts of protein were eluted with Concanavalin A buffer. After adding a buffer with low sugar concentration (10 mM glucoside) a large amount of apolipoprotein H was recovered. These molecules of apolipoprotein H weakly bound to the lectin. When a higher sugar concentration (500 mM mannoside) was added most of the sample applied was eluted. These molecules of apolipoprotein H firmly bound to the column having high affinity for the lectin. These results combined with those coming from the digoxigen-labeled lectins method enable us to understand the inner structure of carbohydrate chains with their outer branches. Molecules of apolipoprotein H which weakly bind to Concanavalin A could bear complex N-glycans organized in biantennary or truncated hybrid structures. Firmly bound apolipoprotein H referred to molecules rich in N-glycan hybrid structures. They have an outer branch belonging to the high mannose carbohydrate chains which explain the ability to bind to the column and an other main branch bearing the sequence galactose beta-(1-4)-N-acetylglucosamine beta-(1-2) mannose. Galactose could be the terminal sugar or, alternatively, be masked with sialic acid alpha-(2-6) terminally linked.
 ...
PMID:Characterization and representative structures of N-oligosaccharides bound to apolipoprotein H. 952 27

Apolipoprotein H is a single chain polypeptide composed of 326 amino acids highly glycosylated. Its carbohydrate content is approximately 19% of the molecular weight. We show that it is rich in sialic acid linked alpha (2-6) to galactose or N-acetylgalactosamine. Sialic acid is not alpha (2-3) linked to galactose. Galactose is beta (1-4) linked to N-acetylglucosamine and beta (1-3) linked to N-acetylgalactosamine. Carbohydrate O-linked chains (mainly sialic acid) are alpha (2-6) linked to galactose or N-acetylgalactosamine. Galactose is also organised in O-linked chains and beta (1-4) linked to N-acetylglucosamine and beta (1-3) linked to acetylgalactosamine. Concanavalin A lectin was used to isolate two groups of apolipoprotein H molecules bearing biantennary and truncated hybrids and high mannose and hybrid oligosaccharides. Apolipoprotein H fails to bind lysine-Sepharose. Our results thus show that it presents truncated hybrid or hybrid-type carbohydrate chains which bear few unmasked mannose residues as a terminal sugar. Biochemical analysis of carbohydrate structures conducted on single isoforms separated through IEF revealed that no specific carbohydrate complex is bound to a single isoform.
 ...
PMID:Study of the glycosylation of apolipoprotein H. 1070 Oct 81