FIG. 1.

hCD79b/GH locus and expression of CD79b in human B-cell lines. A. The hCD79b/GH locus on human chromosome 17q22-24. Vertical arrows indicate the positions of DNase I HS previously identified in chromatin of pituitary somatotropes and placental STB. HSI and HSII are pituitary gland specific, and HSIV is placenta specific. The horizontal arrows indicate the direction of transcription from each gene. The corresponding tissue specificities are noted. B. CD79b expression in developmental-stage human B-cell lines. RNA samples from the K562 human erythroleukemia cell line and from a series of established human B-cell lines were analyzed by Northern blotting. The identity of each B-cell line and its reported stage of differentiation along the B-cell lineage is noted above the respective lanes. The membrane was hybridized with ³²P-cDNA probes to human CD79b mRNA and to mouse ribosomal protein 32 (mRPL32) mRNA as a loading control. The expected positions of the two mRNA signals are noted to the left of the autoradiograph.