A PUTATIVE H-K+-ATPASE IS SELECTIVELY EXPRESSED IN SURFACE EPITHELIAL-CELLS OF RAT DISTAL COLON()

Recently a putative distal colon H+-K+-ATPase alpha-subunit has been i dentified and characterized (M. S. Crowson and G1. E. Shull. J. Biol. Chem. 267: 13740-13748, 1992). In the present study, we report the tis sue and cell expression of this putative H+-K+-ATPase. The results ind icate that, first, in the gut, the putative H+-K+-ATPase alpha-subunit is restricted to the distal part of the colon and is predominantly ex pressed in surface epithelial cells, in marked contrast to the alpha1- subunit of Na+-K+-ATPase that is also expressed in glands. These data suggest that the H+-K+-ATPase alpha-subunit is a potential marker for terminal differentiation of distal colon. Second, in the uterus, the p utative H+-K+-ATPase is restricted to the region of the myometrium bet ween the inner and midmuscular zone that is very rich in vascular supp ly and nerve cells. This striking expression suggests that the H+-K+-A TPase may not be involved in the control of pH and potassium concentra tion of the uterine fluid but rather in distinct functions of vascular and/or nerve cells. Third, with the use of three independent and diff erent approaches (Northern blot analysis, ribonuclease protection assa y, and in situ hybridization), we were unable to detect any significan t amount of H+-K+-ATPase transcripts in kidney tissue. Our data sugges t that the putative distal colon H+-K+-ATPase is probably distinct fro m the kidney isoform. Finally, we report the sequence of a set of dege nerate oligonucleotides that are useful to clone alpha-subunits of the Na+-K+-/H+-K+-ATPase gene family in different tissues and different s pecies.