Shapes, domain organizations and flexibility of laminin and fibronectin, two multifunctional proteins of the extracellular matrix

Engel, Jürgen; Odermatt, Erich K.; Engel, Andréas; Madri, Joseph A.; Furthmayr, Heinz; Rohde, Heilwig; Timpl, Rupert

doi:10.1016/0022-2836(81)90326-0

Cited by 645 publications

(335 citation statements)

References 43 publications

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“…About 43% of the molecules fall into the range between 33 and 36 nm. The diameters of the head and the tail cannot be accurately determined from these pictures [8]. Negatively stained samples ( fig.1 f) do not exhibit the high contrast of rotatory shadowed specimen; however, their diameters are more precisely represented.…”

Section: Introduction 2 Materials and Methodsmentioning

confidence: 95%

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Size and shape of human CI‐inhibitor

1981

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Section: Introduction 2 Materials and Methodsmentioning

confidence: 95%

“…Sample preparation for the electron microscope was done essentially as in [8]. The rotatory shadowing technique as well as the negative staining method was employed.…”

Section: Introduction 2 Materials and Methodsmentioning

confidence: 99%

Size and shape of human CI‐inhibitor

1981

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“…3C and Smith et al, 2007 (Oberhauser et al, 2002). If three modules are unfolded mechanically, an extended Fn molecule which is estimated to be 130 nm in length prior unfolding (Engel et al, 1981), would thus increase in length to 206 nm (130+3 * (28.5-3.2)), or 1.6-fold. Interestingly, Fig.…”

Section: High Extensions Of Fn Fibers Involve Module Unfoldingmentioning

confidence: 99%

Assay to mechanically tune and optically probe fibrillar fibronectin conformations from fully relaxed to breakage

et al. 2008

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In response to growing needs for quantitative biochemical and cellular assays that address whether the extracellular matrix (ECM) acts as a mechanochemical signal converter to co-regulate cellular mechanotransduction processes, a new assay is presented where plasma fibronectin fibers are manually deposited onto elastic sheets, while force-induced changes in protein conformation are monitored by fluorescence resonance energy transfer (FRET). Fully relaxed assay fibers can be stretched at least 5-6 fold, which involves Fn domain unfolding, before the fibers break. In native fibroblast ECM, this full range of stretch-regulated conformations coexists in every field of view confirming that the assay fibers are physiologically relevant model systems. Since alterations of protein function will directly correlate with their extension in response to force, the FRET vs. strain curves presented herein enable the mapping of fibronectin strain distributions in 2D and 3D cell cultures with high spatial resolution. Finally, cryptic sites for fibronectin's N-terminal 70-kD fragment were found to be exposed at relatively low strain, demonstrating the assay's potential to analyze stretch-regulated protein-rotein interactions.

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“…The data indicate that basement membranes may contain more than 100 different polypeptide chains [14]. Only a few of these components have been characterized including a sulfated polypeptide entactin [15,16], a disulfide-bonded protein characteristic for epithelium [I71 and bullous pemphigoid antigen [18].The mouse EHS (Engelbreth-Holm-Swarm) sarcoma which produces large amounts of a basement membrane matrix [19] has been recently used for the identification and structural characterization of collagen type IV [7,20], laminin [4,21,22] and proteoglycans [ti]. Here, we describe a new protein of smaller size which is an ubiquitous constituent of basement membranes.…”

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Nidogen: a new, self‐aggregating basement membrane protein

Timpl

Dziadek

Fujiwara

et al. 1983

European Journal of Biochemistry

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Nidogen was purified from a mouse tumor basement membrane where it accounted for 2 -3 of the total proteins. It was isolated as two forms (A and B) of a monomer (Mr = 80000) each consisting of a single polypeptide chain folded into a globular head connected to a small tail. The B form of the monomer was shown to be capable of aggregating into a nest-like structure (Mr > 250000). A smaller form (M, = 45000) was observed in some of the extracts. The amino acid composition of nidogen was different to that of other basement membrane proteins. It contained about 10 % carbohydrate, with N-linked and 0-linked oligosaccharide chains in similar proportions.Isoelectrofocussing demonstrated a limited heterogeneity of nidogen with PI in the range 6.5 -7. Monomeric nidogen failed to interact with other basement membrane components and heparin. Aggregation could be induced by limited proteolysis and was reversed by detergents or high salt concentrations. Together with the observation that most of the nidogen could be solubilized only after destroying the collagenous matrix, the data indicate that aggregation of nidogen reflects an activity involved in matrix assembly. Specific antibodies raised against nidogen did not distinguish between the monomeric and aggregated form of the protein but showed that the fragment was antigenically deficient. These antibodies did not cross-react with collagen type IV, laminin, entactin and heparansulfate proteoglycan. Immunofluorescence staining and absorption studies demonstrated that nidogen is a common component of authentic basement membranes. Larger forms of nidogen (Mr about 100000 and 150000) were found in organ cultures of Reichert's membrane suggesting that it is synthesized in precursor forms.Basement membranes are extracellular sheets of proteins in close vicinity to epithelial, endothelial, muscle and other cells of the body. They separate these cells from underlying connective tissue and serve as major filtration barriers and for maintaining a proper tissue organization [1,2]. Major components of basement membranes are collagen type IV [3], laminin [4] and heparansulfate proteoglycan [5, 61. The collagenous proteins are responsible for the mechanical stability of these matrices and are integrated in a kind of a network using their terminal domains for self-assembly [7]. Laminin and proteoglycan have the ability to interact with each other and presumably mediate binding of cells to the network [2,8,9]. The precise architecture of these extracellular structures has not yet been elucidated. The difficulties of structural studies are due in part to the complexity and extraordinary size (length 100 -400 nm) of the known components, but also to the incomplete knowledge of additional constituents which, although minor by weight, may nevertheless be important for the structural integrity and function of basement membranes.A considerable diversity of basement membrane components was indicated in previous immunological studies [3,10] and in electrophoretic analyses of glomerular and other...

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Shapes, domain organizations and flexibility of laminin and fibronectin, two multifunctional proteins of the extracellular matrix

Cited by 645 publications

References 43 publications

Size and shape of human CI‐inhibitor

Size and shape of human CI‐inhibitor

Assay to mechanically tune and optically probe fibrillar fibronectin conformations from fully relaxed to breakage

Nidogen: a new, self‐aggregating basement membrane protein

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