MICROFIBRIL-ASSOCIATED GLYCOPROTEIN - CHARACTERIZATION OF THE BOVINE GENE AND OF THE RECOMBINANTLY EXPRESSED PROTEIN

Microfibrils having a diameter of 10-12 nm, found either in associatio n with elastin or independently, are an important component of the ext racellular matrix of many tissues. Because isolation of native protein s composing the microfibrils has proven difficult, information on stru cture/function relationships is limited. In order to extend our unders tanding of the 31-kDa microfibril-associated glycoprotein (MAGP), the bovine gene has been cloned and characterized and the protein has been expressed in a eukaryotic system. The compact coding portion of the g ene is contained in 4.5 kbp of genomic DNA and does not appear to shar e any domain motifs with other known proteins. The size, amino acid co mposition, and sequence of the amino terminus of the secreted recombin ant protein (rMAGP) all agree with values predicted by the nucleotide sequence of the cDNA used in the expression vector. The rMAGP reacts w ith a monospecific antibody prepared against a defined amino acid sequ ence of the natural molecule and reacts specifically with recombinantl y produced tropoelastin, suggesting that rMAGP will be a useful reagen t with which to study its interaction with other extracellular matrix components.