Partial primary structure of bovine plasma fibronectin: Three types of internal homology

Abstract

Approximately one-half of the amino acid sequence (911 amino acid residues out of 1,880 expected) for bovine plasma fibronectin (cold-insoluble globulin) has been determined. Three types of internal homology were identified, showing that a number of partial gene duplications (multiplications) have occurred during the evolution of this protein. Digestion of fibronectin with plasmin results in major fragments with molecular masses of 29, 170,23, and 6 kilodaltons (kDal). The NH2-terminal 29-kDal fragment consists of259 residues ordered as five mutually homologous domains (type I homology) with two disulfide bonds in each domain. The 170-kDal fragment shows two to three bands after NaDodSO4 gel electrophoresis, indicating heterogeneity. This fragment contains the gelatin binding site and the strong heparin binding site present in fibronectin. Digestion of the 170-kDal fragment with chymotrypsin liberates a 45-kDal fragment that also binds to gelatin. This fragment contains at least one domain oftype I homology and two domains of type II homology. Further digestion of the 170-kDal fragment with chymotrypsin results in the formation of a 30-kDal fragment that retains the heparin binding activity. This fragment contains sequences constituting type m homology. The 23-kDal fragment consists of 178 residues having three domains of type I homology. The 6-kDal fragment consists oftwo identical peptides of26 residues, and these two peptides are linked to each other by two disulfide bonds that form the interchain bridges. Another one ofthe peptides for which the sequence was determined links the COOH-terminus of the 29-kDal fragment to the NH2-terminus of the 170-kDal fragment. This and the fact that the COOH-terminal residue of the 6-kDal fragment is a glutamic acid residue order the four plasmin-digestion fragments as 29-, 170-, 23-, and 6-kDal in the intact fibronectin molecule.Fibronectin is a protein or a group of similar proteins found in blood plasma (1) and on the surface of different cell types (2) (for review, see refs. 3-5). The functions attributed to fibronectin, such as cell adhesion to substratum, cell spreading, opsonization of bacteria and other particulate matter, and wound healing, are all related to its affinity to cell surfaces. Binding to vastly different biological compounds, such as gelatin (6), glycosaminoglycans (7), DNA (8), fibrin (9), actin (10), sphingolipids (11), acetyl cholinesterase (12), amyloid P component (13), and complement factor Clq (14), has been demonstrated. Some of these binding sites have been found to be contained in specific fragments generated by limited proteolysis of fibronectin (15)(16)(17)(18)(19)(20)(21)(22)(23)(24). Recently, a transformation-enhancing activity has been shown in the gelatin binding fragments offibronectin (25).Fibronectin is a substrate for blood coagulation factor XIIIa (26) and can be covalently crosslinked to fibrin (26), collagen (21), and the surface ofStaphylococcus aureus (22) by this transglutaminase. Fibronectin used to be known as cold...

The mouse neuronal cell surface protein F3: a phosphatidylinositol-anchored member of the immunoglobulin superfamily related to chicken contactin.

“…Ranscht (1988) has already shown for contactin that the premembrane region contains two segments that share sequence similarity with type III repeats of fibronectin. Most of the residues shared between contactin and fibronectin were also conserved in F3 and alignment of the first (position 768-846) and the second (position 846-946) segment of the deduced F3 protein sequence matched a type III repeat fibronectin sequence (Peterson et al, 1983) at 24 and 23 % of the positions, respectively (results not shown).…”

“…The Ig domains are followed by a segment of"o400 amino acids which contains two regions of •85 residues each which exhibit similarity to fibronectin type III repeats involved in cell and heparin binding (Peterson et al, 1983;Kornblihtt et al, 1984;Odermatt et al, 1985;Obara et al, 1988). A conspicuous Pro-Gly repeat and a stretch of five Figure 7.…”

Comparison of the fibrin-binding activities in the N- and C-termini of fibronectin

“…Fn is secreted as a dimer of two nearly identical polypeptide chains of approximately 220-250 kDa that are linked together by two disulphide bonds near the C-terminus of the protein. Similar to many proteins of the extracellular matrix, Fn is a mosaic protein composed of three types of repeating modular consensus amino acid sequences, referred to as F1, F2 and F3 [3][4][5][6][7][8][9]. In Fn, the modules are organized into proteolytically resistant functional domains that contain binding sites for extracellular matrix proteins, cell-surface receptors, circulating blood proteins, glycosaminoglycans, proteoglycans and certain bacteria.…”

“…The twelve F1 modules of Fn are encoded by a single exon (except "#F1), consist of approximately 45 amino acids, and share between 22 and 55 % sequence identity [1][2][3][5][6][7]. They occur in the N-terminal ("F1-&F1), the collagen-binding ('F1."F2.#F2.…”

Complete primary structure of the collagen-binding domain of bovine fibronectin

“…Three glucosamine-based oligosaccharide groups are attached to Asn-399, Asn-497 and to Asn-511, respectively. Two of the three types (I and 11) [Petersen et al (1983) Proc. Natl Acad.…”