title: Complete sequence and in vitro expression of a tissue-specific phosphatidylinositol-linked N-CAM isoform from skeletal muscle.
abstract: Neural cell adhesion molecules (N-CAMs) are a family of cell surface sialoglycoproteins encoded by a single copy gene. A full-length cDNA clone that encodes a nontransmembrane phosphatidylinositol (PI) linked N-CAM of Mr 125 x 10(3) has been isolated from a human skeletal muscle cDNA library. The deduced protein sequence encodes a polypeptide of 761 amino acids and is highly homologous to the N-CAM isoform in brain of Mr 120 x 10(3). The size difference between the 125 x 10(3). The size difference between the 125 x 10(3) Mr skeletal muscle form and the 120 x 10(3) Mr N-CAM form from brain is accounted for by the insertion of a block of 37 amino acids called MSD1, in the extracellular domain of the muscle form. Transient expression of the human cDNA in COS cells results in cell surface N-CAM expression via a putative covalent attachment to PI-containing phospholipid. Linked in vitro transcription and translation experiments followed by immunoprecipitation with anti-N-CAM antibodies demonstrate that the full-length clone of 761 amino acid coding potential produces a core polypeptide of Mr 110 x 10(3) which is processed by microsomal membranes to yield a 122 x 10(3) Mr species. Taken together, these results demonstrate that the cloned cDNA sequence encodes a lipid-linked, PI-specific phospholipase C releasable surface isoform of N-CAM with core glycopeptide molecular weight corresponding to the authentic muscle 125 x 10(3) Mr N-CAM isoform. This is the first direct correlation of cDNA and deduced protein sequence with a known PI-linked N-CAM isoform from skeletal muscle.
authors.affiliation: Institute of Neurology, London, UK.
authors.forename: C H
authors.initials: CH
authors.lastname: Barton
authors.forename: G
authors.initials: G
authors.lastname: Dickson
authors.forename: H J
authors.initials: HJ
authors.lastname: Gower
authors.forename: L H
authors.initials: LH
authors.lastname: Rowett
authors.forename: W
authors.initials: W
authors.lastname: Putt
authors.forename: V
authors.initials: V
authors.lastname: Elsom
authors.forename: S E
authors.initials: SE
authors.lastname: Moore
authors.forename: C
authors.initials: C
authors.lastname: Goridis
authors.forename: F S
authors.initials: FS
authors.lastname: Walsh
mesh_terms: D000595:Amino Acid Sequence; D000954:Antigens, Surface; D001483:Base Sequence; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules; D005803:Genes, Immunoglobulin; D006801:Humans; D007527:Isoenzymes; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009132:Muscles / Q000201:enzymology*; D010716:Phosphatidylinositols / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D000954:Antigens, Surface; D015815:Cell Adhesion Molecules; D007527:Isoenzymes; D010716:Phosphatidylinositols; D010738:Type C Phospholipases