Matrilin-2, a large, oligomeric matrix protein, is expressed by a great variety of cells and forms fibrillar networks.
Matrilin-2 is a member of the protein superfamily with von Willebrand factor type A-like modules. Mouse matrilin-2 cDNA fragments were expressed in 293-EBNA cells, and the protein was purified, characterized, and used to immunize rabbits. The affinity-purified antiserum detects matrilin-2 in dense and loose connective tissue structures, subepithelial connective tissue of the skin and digestive tract, specialized cartilages, and blood vessel walls. In situ hybridization of 35S-labeled riboprobes localizes the matrilin-2 mRNA to fibroblasts of dermis, tendon, ligaments, perichondrium, and periosteum; connective tissue elements in the heart; smooth muscle cells; and epithelia and loose connective tissue cells of the alimentary canal and respiratory tract. RNA blot hybridization and immunoblotting revealed both matrilin-2 mRNA and protein in cultures of a variety of cell types, confirming the tissue distribution. Alternative splicing affects a module unique for matrilin-2 in all of the above RNA sources. SDS-polyacrylamide gel electrophoresis and electron microscopy reveals matrilin-2 from tissue extracts and cell line cultures as a mixture of mono-, di-, tri-, and tetramers. Matrilin-2 is substituted with N-linked oligosaccharides but not with glycosaminoglycans. Because of other, yet unidentified, cell-type dependent posttranslational modifications, the monomer is heterogeneous in size. Immunofluorescence showed that matrilin-2 functions by forming an extracellular, filamentous network.
Piecha
D
D
Institute for Biochemistry, Medical Faculty, University of Cologne, D-50931 Cologne, Germany.
Muratoglu
S
S
Mörgelin
M
M
Hauser
N
N
Studer
D
D
Kiss
I
I
Paulsson
M
M
Deák
F
F
D000818:Animals; D001483:Base Sequence; D003238:Connective Tissue / Q000378:metabolism; D017931:DNA Primers; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D064235:Matrilin Proteins; D051379:Mice; D008856:Microscopy, Fluorescence; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000235:genetics
D017931:DNA Primers; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; C577542:Matn2 protein, mouse; D064235:Matrilin Proteins; D012333:RNA, Messenger