Microfibril-associated Protein 4 Is Present in Lung Washings and Binds to the Collagen Region of Lung Surfactant Protein D

We have purified a glycoprotein from bovine lung washings using affinity chromatography on a maltose-affinity column. On SDS-polyacrylamide gel electrophoresis the protein showed a molecular mass of 36 kDa in the reduced state and 66 kDa in the unreduced state. On gel permeation chromatography the a...

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Bibliographic Details
Published in:The Journal of biological chemistry 1999-11, Vol.274 (45), p.32234-32240
Main Authors: Lausen, Mette, Lynch, Nicholas, Schlosser, Anders, Tornøe, Ida, Sækmose, Susanne Gjørup, Teisner, Børge, Willis, Antony C., Crouch, Erika, Schwaeble, Wilhelm, Holmskov, Uffe
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Binding Sites
Calcium - metabolism
Carrier Proteins - isolation & purification
Carrier Proteins - metabolism
Cattle
Chromatography, Affinity
Collagen - metabolism
Electrophoresis, Polyacrylamide Gel
Extracellular Matrix Proteins
Glycoproteins - isolation & purification
Glycoproteins - metabolism
Glycosylation
Humans
Integrins - metabolism
Lung - chemistry
maltose
Mannans - metabolism
MFAP4 protein
Molecular Sequence Data
Molecular Weight
surfactant protein D
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Summary:We have purified a glycoprotein from bovine lung washings using affinity chromatography on a maltose-affinity column. On SDS-polyacrylamide gel electrophoresis the protein showed a molecular mass of 36 kDa in the reduced state and 66 kDa in the unreduced state. On gel permeation chromatography the apparent molecular mass was 250 kDa. N-terminal sequencing showed homology to the human matrix protein microfibril-associated protein (hMFAP4), and the glycoprotein was designated bovine MFAP4 (bMFAP4). Lung surfactant protein D (SP-D) was also purified from lung washings, and calcium-dependent binding was demonstrated between bMFAP4 and SP-D. hMFAP4 was cloned, and recombinant hMFAP4 showed the same binding pattern to SP-D as bMFAP4. No binding was seen to recombinant SP-D composed of the neck region and carbohydrate recognition domain of SP-D, indicating that the interaction between MFAP4 and SP-D is mediated via the collagen region of SP-D. MFAP4 also showed calcium-dependent binding to mannan, which was partially inhibited by maltose. Our findings indicate that MFAP4 has two binding specificities, one for collagen and one for carbohydrate, and we suggest that MFAP4 may fix the collectins in the extracellular compartment during inflammation.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.274.45.32234