. Author manuscript; available in PMC: 2015 Mar 24.

Published in final edited form as: Biochem J. 2010 Dec 1;432(2):407–416. doi: 10.1042/BJ20100041

Table 3.

Ca²⁺/CaM-mediated inhibition of 4.1G interactions with membrane proteins

Analyte	Ligand	Condition	k_a (M⁻¹ s⁻¹)	k_d (s⁻¹)	K_(D) (nM)
4.1G/CaM	band3cyt	EGTA	5.1 ± 0.2 × 10⁵	6.4 ± 0.2 × 10⁻²	127 ± 6
		Ca²⁺	No Binding	No Binding	No Binding^*
	GPCcyt	EGTA	8.4 ± 0.2 × 10⁴	1.3 ± 0.2 × 10⁻²	155 ± 22
		Ca²⁺	1.2 ± 0.1 × 10⁴	1.5 ± 0.1 × 10⁻²	1251 ± 21
	p55	EGTA	11 ± 0.2 × 10⁵	2.3 ± 0.2 × 10⁻²	215 ± 43
		Ca²⁺	No Binding	No Binding	No Binding
	CD44cyt	EGTA	7.1 ± 0.2 × 10⁴	1.4 ± 0.2 × 10⁻²	197 ± 29
		Ca²⁺	No Binding	No Binding	No Binding

K_(D) for the interactions of the complex of 4.1G and CaM (4.1G/CaM) with cytoplasmic domain of band 3 (band 3cyt), that of GPC (GPCcyt), that of CD44 (CD44cyt) or with p55 in the absence (EGTA) or presence of Ca²⁺ (Ca²⁺) are shown. Full length protein 4.1G (at 50 nM to 1 µM) was pre-incubated with CaM (5 µM) and either 0.1 mM EGTA (EGTA) or 1.1 mM CaCl₂ and 1.0 mM EGTA (Ca²⁺) for 30 min at 25 °C in buffer D. The complex of 4.1G and CaM was applied to band 3cyt, GPCcyt, p55 or CD44cyt immobilized on aminosilane cuvettes. k_a, k_d and K_(D) were calculated from three independent experiments represents (mean ± S.D.).

No binding: No signal appeared when 2 µM of Analyte applied to the Ligand immobilized cuvette.