title: Regulation of alpha 2,3-sialyltransferase expression correlates with conversion of peanut agglutinin (PNA)+ to PNA- phenotype in developing thymocytes.
abstract: Staining of thymus tissue with the plant lectin peanut agglutinin (PNA) is a classic technique for defining the cortical (PNA+) and medullary (PNA-) regions of this tissue. These two regions are primarily composed of immature and mature thymocytes, respectively. Conversion of the PNA+ to the PNA- phenotype has been attributed to masking of the cell surface carbohydrate receptors of PNA by sialic acid during the intrathymic maturation of these cells. We present evidence that the regulated expression of a single glycosyltransferase, a Gal beta 1,3GalNAc alpha 2,3-sialyltransferase, can account for this glycosylation change. This enzyme sialylates the preferred ligand of PNA, Gal beta 1,3GalNAc, forming the sequence NeuAc alpha 2,3Gal beta 1,3GalNAc, thus masking PNA binding sites. Expression of the enzyme is inversely proportional to expression of the PNA receptor, as evidenced by analysis of T-lymphoblastoid cell lines and by in situ hybridization experiments in human thymic tissue.
authors.affiliation: Department of Biological Chemistry, UCLA School of Medicine 90024.
authors.forename: W
authors.initials: W
authors.lastname: Gillespie
authors.forename: J C
authors.initials: JC
authors.lastname: Paulson
authors.forename: S
authors.initials: S
authors.lastname: Kelm
authors.forename: M
authors.initials: M
authors.lastname: Pang
authors.forename: L G
authors.initials: LG
authors.lastname: Baum
mesh_terms: D010367:Arachis; D002240:Carbohydrate Sequence; D002454:Cell Differentiation; D002460:Cell Line; D006801:Humans; D037102:Lectins / Q000378:metabolism*; D008969:Molecular Sequence Data; D019887:Peanut Agglutinin; D010641:Phenotype; D037121:Plant Lectins; D012799:Sialyltransferases / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase
chemical_list: D037102:Lectins; D019887:Peanut Agglutinin; D037121:Plant Lectins; D012799:Sialyltransferases; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase