Title : Ceramide UDPgalactosyltransferase from myelinating rat brain: purification, cloning, and expression
Abstract :
- Cerebrosides and sulfatides are major glycosphingolipids of the lipid bilayer of the myelin sheath assembled by oligodendrocytes and Schwann cells during myelination
- Cerebrosides are synthesized by ceramide UDPgalactosyltransferase [CGT ; 2-hydroxyacylsphinogosine 1-beta-galactosyl-transferase ; UDPgalactose:2-(2-hydroxyacyl)sphingosine 1-beta-D-galactosyltransferase ; UDPgalactose:2-(2-hydroxyacyl)sphingosine 1-beta-D-galactosyltransferase , EC 2.4.1.45] with UDPgalactose and ceramide as substrates
- Here we describe a purification method from microsomes of myelinating rat brains that includes ion exchange, dye ligand, and lectin affinity chromatography
- The enzyme was identified as a 64-kDa high-mannose glycoprotein
- A CGT-specific cDNA clone was isolated from a rat brain cDNA library using CGT oligonucleotides derived from peptide sequences
- The cDNA insert encodes a polypeptide of 541 amino acid residues with a molecular weight of 61,126
- The polypeptide has three putative glycosylation sites and one hydrophobic domain at the C terminus
- A 20-residue N-terminal signal sequence is lost during cotranslational translocation
- Northern blot analysis demonstrates that CGT expression is restricted to brain tissue and is time dependent, correlating with myelin basic protein expression
- In situ hybridization reveals that CGT expression is restricted to the oligodendrocyte-containing cell layers of cerebrum and cerebellum, which also express myelin basic protein
- The amino acid sequence of CGT shows significant homology to mammalian UDPglucuronyltransferases, which suggests a common evolutionary origin of these enzymes
Output (sent_index, trigger,
protein,
sugar,
site):
- 2. [CGT, , UDPgalactosyltransferase [CGT, UDPgalactose, -
- 4. glycoprotein, , enzyme, a 64-kDa high-mannose glycoprotein, -
- 7. glycosylation, , -, -, sites
Output(Part-Of) (sent_index,
protein,
site):
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):