Immunoglobulin heavy chain genes: demethylation accompanies class switching.

AUTOR(ES)

Rogers, J

RESUMO

The methylation of immunoglobulin heavy chain genes was examined before and after class switching, by using the Hpa II/Msp I restriction mapping technique. The mu, delta, and gamma 1 genes all are methylated in cells that do not express them but are demethylated when they are expressed. In particular, the delta gene remains methylated, and thus presumably untranscribed, in a cell line that probably represents an early stage of B-cell differentiation and produces only mu heavy chains. Because mu and delta RNAs are cotranscribed from a single complex transcription unit at a later stage of B-cell differentiation, this finding implies that the mu-plus-delta complex transcription unit is of variable length.

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