Isoforms of Na,K-ATPase in Artemia saline: I. Detection by FITC binding and time course.
Partially purified Na,K-ATPase from whole nauplii at various stages of development, analyzed by SDS-PAGE, reveals a polydisperse beta and two alpha subunits (denoted alpha 1 and alpha 2). In the absence of Ca2+, ATP-inhibitable fluorescein isothiocyanate (FITC) labeling is restricted to the alpha subunit of this enzyme, even in crude naupliar homogenates. The intensity of the alpha-specific fluorescent signal (i.e., the sum of the yield from both alpha isoforms) is proportional to Na,K-ATPase activity during development. FITC-labeled subunits were detected at 8 hr of development prior to the detection of measurable Na,K-ATPase activity. The alpha 2/alpha 1 ratio changed from an initial value of 1.25 to a peak of 1.75 at 32 hr of development, then reverted to a ratio of 1.25 by 42 hr, and remained constant thereafter. Pulse chase studies with 35S-methionine indicated that the developmental increase in enzyme activity is coincident with amino acid incorporation into the alpha subunits, implying that enzyme synthesis is active during enzyme accumulation.
Salon
J
J
Department of Biochemistry & Molecular Biophysics, College of Physicians & Surgeons, Columbia University, New York, New York 10032.
Cortas
N
N
Edelman
I S
IS
D000818:Animals; D001156:Artemia / Q000201:enzymology*; D003720:Densitometry; D004591:Electrophoresis, Polyacrylamide Gel; D016650:Fluorescein-5-isothiocyanate; D005452:Fluoresceins / Q000378:metabolism; D007422:Intestines / Q000166:cytology / Q000201:enzymology; D007527:Isoenzymes / Q000032:analysis / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D012491:Salt Gland / Q000166:cytology / Q000201:enzymology; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis / Q000378:metabolism*; D013861:Thiocyanates / Q000378:metabolism; D013997:Time Factors
D005452:Fluoresceins; D007527:Isoenzymes; D013861:Thiocyanates; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D016650:Fluorescein-5-isothiocyanate