Entactin (nidogen), a 150-kD sulfated glycoprotein, is a major component of basement membranes and forms a highly stable noncovalent complex with laminin. The complete amino acid sequence of mouse entactin has been derived from sequencing of cDNA clones. The 5.9-kb cDNA contains a 3,735-bp open reading frame followed by a 3'-untranslated region of 2.2 kb. The open reading frame encodes a 1,245-residue polypeptide with an unglycosylated Mr of 136,500, a 28-residue signal peptide, two Asn-linked glycosylation sites, and two potential Ca2+-binding sites. Analysis of the deduced amino acid sequence predicts that the molecule consists of two globular domains of 70 and 36 kD separated by a cysteine-rich domain of 28 kD. The COOH-terminal globular domain shows homology to the EGF precursor and the low density lipoprotein receptor. Entactin contains six EGF-type cysteine-rich repeat units and one copy of a cysteine-repeat motif found in thyroglobulin. The Arg-Gly-Asp cell recognition sequence is present in one of the EGF-type repeats, and a synthetic peptide from the putative cell-binding site of entactin was found to promote the attachment of mouse mammary tumor cells.
Amino acid sequence and domain structure of entactin. Homology with epidermal growth factor precursor and low density lipoprotein receptor.
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M E Durkin, S Chakravarti, B B Bartos, S H Liu, R L Friedman, A E Chung; Amino acid sequence and domain structure of entactin. Homology with epidermal growth factor precursor and low density lipoprotein receptor.. J Cell Biol 1 December 1988; 107 (6): 2749–2756. doi: https://doi.org/10.1083/jcb.107.6.2749
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