Molecular characterization of the Schwann cell myelin protein, SMP: structural similarities within the immunoglobulin superfamily.
The Schwann cell myelin protein (SMP), previously defined in quail and chick by a monoclonal antibody, is in vivo exclusively expressed by myelinating and nonmyelinating Schwann cells and oligodendrocytes. The isolation of the complete nucleotide sequence of SMP is reported here. The predicted polypeptide chain reveals that SMP is a transmembrane molecule of the immunoglobulin superfamily showing sequence similarities with several surface glycoproteins expressed in the nervous and immune systems. In spite of a 43.5% overall sequence identity between rat myelin-associated glycoprotein (MAG) and quail SMP, SMP does not seem to be the avian homolog of MAG, since their expression, regulation, and functions are significantly different. Unusual sequence arrangements shared by SMP, MAG, and two lymphoid antigens suggest the existence of a particular subgroup in the immunoglobulin superfamily.
Dulac
C
C
Institut d'Embryologie du CNRS et du College de France, Nogent-sur-Marne.
Tropak
M B
MB
Cameron-Curry
P
P
Rossier
J
J
Marshak
D R
DR
Roder
J
J
Le Douarin
N M
NM
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D015815:Cell Adhesion Molecules / Q000032:analysis* / Q000235:genetics; D002645:Chickens; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D007136:Immunoglobulins / Q000032:analysis* / Q000235:genetics; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics; D008969:Molecular Sequence Data; D009185:Myelin Proteins / Q000032:analysis* / Q000235:genetics; D018992:Myelin-Associated Glycoprotein; D063308:Myelin-Oligodendrocyte Glycoprotein; D009836:Oligodendroglia / Q000737:chemistry; D016133:Polymerase Chain Reaction; D011784:Quail; D012583:Schwann Cells / Q000737:chemistry*; D012689:Sequence Homology, Nucleic Acid
D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C571328:Mog protein, rat; D009185:Myelin Proteins; D018992:Myelin-Associated Glycoprotein; D063308:Myelin-Oligodendrocyte Glycoprotein; C104891:SMP protein, Schwann cell, Coturnix coturnix; D004247:DNA