Expression of the beta-subunit isoforms of the Na,K-ATPase in rat embryo tissues, inner ear and choroid plexus.
We report evidence of the apical localization of the two Na,K-ATPase beta-subunit isoforms in cells of the inner ear and of the choroid plexus of the rat. To this end, we generated isoform-specific antisera against the human Na,K-ATPase beta 1 and beta 2 subunits. These polyclonal rabbit antisera were raised against truncated beta-isoform proteins that were made in E coli with pET expression vectors. Deglycosylation of the native antigen with N-endoglycosidase F shows four bands in the beta 1 isoform and five bands in the beta 2 isoform immunoblots. In E15 rat embryos, the beta 1 isoform was detected in brain, heart and kidney and the beta 2 isoform only in brain. While beta-subunit mRNA expression (Watts AG, Sanchez-Watts G, Emanuel JR, Levenson R (1991) Proc Natl Acad Sci USA 88, 7425-7429), immunoblotting and enzymatic activity have been determined (Zlokovic BV< mackic JB, Wang L, McComb JG, McDonough A (1993) J Biol Chem 268, 8019-8025), very little is known about the specific localization of each beta-isoform in the epithelia of choroid plexus and inner ear. Immunocytochemical preparations of 15-day-old whole rat embryos and adult rat brain showed an enhanced staining for the beta 1 and beta 2 isoforms in the apical membrane of the ampullary crests of the inner ear's semicircular ducts and in the cuboidal cells of the choroid plexus.
González-Martínez
L M
LM
Departamento de Bioquímica y Biología Molecular, Universidad de La Laguna, Tenerife, Spain.
Avila
J
J
Martí
E
E
Lecuona
E
E
Martín-Vasallo
P
P
D000818:Animals; D015153:Blotting, Western; D002831:Choroid Plexus / Q000196:embryology / Q000201:enzymology*; D007758:Ear, Inner / Q000196:embryology / Q000201:enzymology*; D004622:Embryo, Mammalian / Q000201:enzymology*; D005260:Female; D006031:Glycosylation; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D007527:Isoenzymes; D000254:Sodium-Potassium-Exchanging ATPase