Chararacterization of G-protein α subunits in the G_q class: Expression in murine tissues and in stromal and hematopoietic cell lines

Murine Gα14 and Gα15 cDNAs encode distinct α subunits of heterotrimeric guanine nucleotide-binding poteins (G proteins). These α subunits are related to members of the G_q class and share certain sequence characteristics with Gα_q Gα11, and Gα16, such as the absence of a pertussis toxin ADP-ribosylation site. Gα11 and Gα_q are ubiquitously expressed among murine tissues but α14 is predominantly expressed in spleen, lung, kidney, and testis whereas Gα15 is pimarily restricted to hematopoietic lineages. Among hematopotetic cell lines, Gα11 mRNA is found in all cell lines tested, Gα_q is expressed widely but is not found in most T-cell lines, Gα15 is predominantly expressed in myeloid and B-cell lineages, and Gα14 is expressed in bone marrow adherent (stromal) cells, certain early myeloid cells, and progenitor B cells. Polyclonal antisera produced from synthetic peptides that correspond to two regions of Gα15 react with a protein of 42 kDA expressed in B-cell membranes and in Escherichia coli transformed with Gα15 cDNA. The expression patterns that were observed in mouse tissues and cell lines indicate that each of the α subunits in the G_q class may be involved in pertussis toxin-insensitive signal-transduction pathways that are fundamental to hematopoietic cell differentiation and function.