Purification and characterization of two high-affinity (adenosine 3',5'-monophosphate)-binding proteins from yeast. Identification as multiple forms of glyceraldehyde-3-phosphate dehydrogenase.
Two high-affinity cAMP-binding proteins (I and II) have been purified to homogeneity from baker's yeast by a procedure avoiding proteolytic damage. These proteins have been identified as multiple forms of glyceraldehyde-3-phosphate dehydrogenase. The two cAMP-binding proteins are similar in affinities for cAMP, have identical elution volumes on gel filtration, and contain one type of subunit (Mr 37 500). The form II of glyceraldehyde-3-phosphate dehydrogenase is free of NAD+ and has a Kd of 1.3 X 10(-6) M with respect to cAMP. A marked concentration-dependent self-association of the subunits of the form-II protein was revealed by Yphantis sedimentation equilibrium studies. Significant monomer concentrations are present at total concentrations less than 0.02 mg/ml. Conventional sedimentation equilibrium analyses indicated a tetramer Mr of 170 000. The high-affinity binding of cAMP to glyceraldehyde-3-phosphate dehydrogenase may significantly reduce intracellular cAMP levels and is also discussed in relation to the nature of eukaryote cAMP-binding proteins with similar native or subunit Mr values which are at present functionally undefined.
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000302:isolation & purification / Q000378:metabolism*; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D011953:Receptors, Cyclic AMP / Q000302:isolation & purification / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
D007527:Isoenzymes; D011953:Receptors, Cyclic AMP; D000242:Cyclic AMP; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D015105:3',5'-Cyclic-AMP Phosphodiesterases