NA,K-ATPASE ISOFORM EXPRESSION IN SHEEP RED-BLOOD-CELL PRECURSORS

Isoform expression of mammalian red cell Na,K-ATPase was analyzed using messenger RNA isolated from red cell precursor-enriched bone marrow of anemic sheep. Expression of the catalytic α subunit was analyzed using rat isoform-specific cDNA probes and expression of the β1 subunit, using a sheep β1-specific cDNA probe. RNA isolated from sheep kidney and brain were analyzed concurrently. In the red cell, as in the kidney, messenger RNA encoding only one isoform (α1) of the catalytic subunit is detected; neither of the other isoforms (α2 or α3) could be detected. This holds true for bone marrow of sheep of either the low potassium or high potassium phenotype. Relative to the expression of α1, β subunit-specific message (β1) was extremely low in the red cell compared to either kidney (< 5%) or brain (< 3%). Using a rat cDNA probe specific for a β1-like subunit, β2, message was detected in brain but not in either kidney or bone marrow. © 1990.