Oligomerization of the plasma membrane calcium pump involves two regions with different thermal stability

• Published in: FEBS letters 2000-10, Vol.483 (2), p.99-103
• Main Authors: Levi, Valeria, Rossi, Juan P.F.C., Castello, Pablo R., González Flecha, F.Luis
• Format: Article
• Language: English
• Subjects: Binding Sites; C28W, synthetic peptide corresponding to the sequence 1086–1113 of the hPMCA4b; Calcium pump; Calcium-Transporting ATPases - chemistry; Calcium-Transporting ATPases - metabolism; Calmodulin; Calmodulin - metabolism; Calmodulin-Binding Proteins - chemistry; Calmodulin-Binding Proteins - metabolism; CaM, calmodulin; Dimerization; EITC, eosin-5′-isothiocyanate; Erythrocyte Membrane - enzymology; FITC, fluorescein-5′-isothiocyanate; Fluorescence; FRET, fluorescence resonance energy transfer; hPMCA4b, isoform 4b of the human plasma membrane calcium pump; Humans; Kinetics; Membrane protein; MOPS, 3-(N-morpholino)-propanesulfonic acid; Oligomerization; Plasma membrane calcium pump; PMCA, human plasma membrane calcium pump; PMSF, phenylmethyl-sulfonyl fluoride; Protein Binding; Protein Folding; Spectrometry, Fluorescence; Thermal stability; Thermodynamics
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(00)02093-7

Ca 2+ pump dimerization was studied by using a combined approach of thermal denaturation and fluorescence resonance energy transfer. The measurement of calcium pump ability to dimerize after the unfolding of individual functional domains of the enzyme demonstrated the existence of two different regions involved in the self-association process. One of these regions is highly susceptible to thermal unfolding and was identified as the calmodulin (CaM)-binding domain. The other region whose thermal stability is higher than those of the catalytic and CaM-binding domains could be related with the previously found C28W-binding regions.