Biochemical and structural studies of tenascin/hexabrachion proteins.

Journal Article

Tenascin is a large, disulfide-bonded glycoprotein of the extracellular matrix. The predominant form of tenascin observed by electron microscopy is a six-armed oligomer, termed a hexabrachion. We have determined the molecular mass of the native human hexabrachion to be 1.9 x 10(6) Da by sedimentation equilibrium analysis and by electrophoresis on non-reducing agarose gels. On reducing polyacrylamide gel electrophoresis (SDS-PAGE), human tenascin showed a single prominent band at 320 kDa and minor bands of 220 and 230 kDa. The molecular weight of the native human hexabrachion is thus consistent with a disulfide-bonded hexamer of the 320 kDa subunits. Upon treatment with neuraminidase, the apparent molecular weights of all human and chicken tenascin subunits on reducing SDS-PAGE were decreased by about 10 kDa. Prolonged incubation with alpha-mannosidase, however, caused no apparent change in the apparent molecular weight of tenascin subunits. Sedimentation in a cesium chloride gradient gave a higher buoyant density for human tenascin than for fibronectin, suggesting that it has a higher degree of glycosylation. The far-UV circular dichroism spectrum indicates a predominance of beta-structure and a lack of collagen-like or alpha-helical structure. When human hexabrachions were reduced and acetylated, the resulting fragments were single arms which sedimented at 6 S in glycerol gradients and migrated at 320 kDa on non-reducing gels. Treatment of tenascin with trypsin and alpha-chymotrypsin also produced large fragments which were fractionated by gradient sedimentation and analyzed by non-reducing SDS-PAGE and electron microscopy. We present a structural model for the assembly of the observed fragments into the elaborate native hexabrachion.

Full Text

Duke Authors

Cited Authors

  • Taylor, HC; Lightner, VA; Beyer, WF; McCaslin, D; Briscoe, G; Erickson, HP

Published Date

  • October 1989

Published In

Volume / Issue

  • 41 / 2

Start / End Page

  • 71 - 90

PubMed ID

  • 2482292

International Standard Serial Number (ISSN)

  • 0730-2312

Digital Object Identifier (DOI)

  • 10.1002/jcb.240410204

Language

  • eng

Conference Location

  • United States