The Geonomic Organization of the CD28 Gene. Implications for the Regulation of CD28 mRNA Expression and Heterogeneity

CD28 is a 90-kDa homodimeric glycoprotein present on the surface of a large subset of T cells that appears to play an important role in the modulation of T cells activation. Although a number of physiologic effects associated with CD28 stimulation have been defined, relatively less is known about th...

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Bibliographic Details
Main Authors: Lee, Kelvin P, Taylor, Carol, Petryniak, Bronislawa, Turka, Laurence A, June, Carl H
Format: Report
Language:English
Subjects:
ACTIVATION
CELLS
GENES
GLYCOPROTEINS
HYPOTHESES
MEDICINE
Medicine and Medical Research
MODULATION
PE62233N
PHYSIOLOGICAL EFFECTS
PLASMAS(PHYSICS)
PROTEINS
RECORDS
STEADY STATE
T LYMPHOCYTES
WU1051
WUDN249507
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Summary:CD28 is a 90-kDa homodimeric glycoprotein present on the surface of a large subset of T cells that appears to play an important role in the modulation of T cells activation. Although a number of physiologic effects associated with CD28 stimulation have been defined, relatively less is known about the structure and expression of the CD28 gene itself. We now show that CD28 is expressed in both Th cells and plasma cells as a series of four distinct CD28 mRNA species: 1.3-, 1.5-, 3.5-, and 3.7-kb transcripts. The steady state expression of all four transcripts in CD28+ T cells was stimulated by PMA, suggesting that they might share a common phorbol-sensitive promotor. Consistent with this hypothesis, CD28 was found to be encoded by a single copy gene organized into four exons, each exon defining a functional domain of the predicted protein. All CD28 transcripts appear to initiate within a 61-bp palindrome. Generation of the four CD28 mRNA species from the CD28 gene involves two distinct posttranscriptional events. The longer pair of transcripts (3.5/3.7 kb) is generated by the use of an alternate nonconsensus polyadenylation signal. Pub. in Jnl. of Immunology, v145 n1 p344-352, 1 Jul 1990.