Amino Acid Composition of Calcium-Binding Loops

Amino Acid Composition of the Calcium-Binding Loop in Canonical EF Hands

276 canonical calcium binding loops were examined. 165 unique sequences were identified. The following table shows how often each residue was found in each site in the binding loop. This table was taken from:

Marsden, BJ, GS Shaw, and BD Sykes. (1990) Biochem. Cell. Biol. 68. 587-601. (Table2)

Amino Acid	1	2	3	4	5	6	7	8	9	10	11	12
					Loop Position
	X	*	Y	*	Z	G	#	I	x	*	*	z
asp	162	1	120	5	93	3	4	---	55	1	44	15
asn	1	2	40	15	28	3	4	1	10	2	7	2
glu	1	9	4	5	2	---	10	---	23	16	52	142
gln	---	14	---	7	1	---	9	---	2	3	8	1
ser	---	9	1	---	37	1	10	---	32	6	5	---
thr	---	16	---	---	1	1	21	1	18	9	3	---
gly	---	2	---	84	3	147	2	1	17	6	1	---
lys	---	46	---	23	---	3	22	---	---	10	14	---
arg	---	13	---	10	---	2	5	---	2	6	---
his	---	---	---	7	---	2	1	1	---	---	---	---
ala	---	16	---	8	---	1	6	1	1	17	17	---
val	---	13	---	---	---	---	6	21	1	19	1	4
leu	---	5	---	---	---	2	5	15	1	16	1	1
ile	---	10	---	---	---	---	4	116	---	6	1	---
tyr	1	1	---	---	---	---	24	---	---	13	2	---
phe	---	4	---	---	---	---	26	---	---	27	---	---
cys	---	2	---	---	---	---	2	3	1	---	---	---
met	---	2	---	1	---	---	3	4	2	1	2	---
pro	---	---	---	---	---	---	1	1	---	5	7	---
trp	---	---	---	---	---	---	---	---	---	2	---	---

Also noted in the same paper:

positions 1,3,5,6,8, and 12 are the most highly conserved
most loops (106/165) have four acidic residues in them