Sugar-binding F-box proteins - sequence alignment

Sequence alignment of Fbs-type F-box associated domains in F-box proteins.  The domain is also found in some polypeptides without F-boxes, but such domains are not included in the alignment.  Proteins containing an F-box together with an Fbs-type F-box associated domain are found in a range of vertebrates.  Although elements of the glycosylation and protein targeting machinery are conserved in lower eukaryotes, the F-box associated domain is not present in proteins from yeast, slime mold or fruit fly.  Surprisingly, one protein with an F-box domain in the relevant architectural context is present in the invertebrate C elegans.  Included in the alignment are all human and murine proteins, plus a selection of other vertebrate proteins and the example from C elegans.

 

Regions of secondary structure are indicated above the alignment and coloured to correspond with the structure of murine Fbs1/Fbx2, left.  Alpha-helices (a1,2) are highlighted in red, beta-strands in one beta-sheet (b1,4,6,7,9) in yellow, and beta-strands in the opposite beta-sheet (b2,3,5,8,10) in blue.  Residues that are identical in over 75% of the aligned sequences are highlighted in green.  Residues that are similar in over 75% of the sequences are highlighted in cyan.  Residues which interact with chitobiose in the Fbs1 structure are highlighted in magenta.  The equivalent residues in other proteins are highlighted in magenta if identical and in pink if the character of the residue is conserved. 

Accession numbers

 

Fbx2 (Fbs1): human Q9UK22 Q5TGY0, mouse Q80UW2, X tropicalis 17406, G gallus 04657.

Fbx6b (Fbs2): human Q9NRD1, mouse Q9QZN4.

Fbx17 (Fbx26 Fbg4): human Q96EF6, mouse Q9QZM8, X tropicalis 05327

Fbx27 (Fbg5): human Q8NI29, mouse Q6DIA9.

Fbx44 (Fbx30 Fbx6a Fbg3): human Q9H4M3, mouse Q8BK26, X tropicalis 27482, 25469 (novel), G gallus 04646.

Fugu 153187; Tetraodon Q4S5T2; C elegans C14B1.3 Q17962.

 

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The sugar ligand is shown in dark blue.  Protein Data Bank structure ID: 1UMI.