Fig. 1. Sequence features of trypanosome clathrin and adaptin. (A) The clathrin
heavy chain. Structural domains of T. brucei (TbCLH) are depicted as
determined on the basis of similarity to human CLH1 (accession no. Q00610) and
yeast CLH (accession no. P22137). GH, globular head; L, flexible linker; DA,
distal arm; PA, proximal arm; LC, light chain binding region; TR,
trimerisation region. Percentage identity/similarity to yeast CLH (Sc) and
human CLH1 (Hs) are given below each domain. The relative locations of each
sheared T. brucei genomic DNA sequence (obtained from the TIGR T.
brucei genome sequencing project website: www.tigr.org/tdb/mdb/tbdb) and
PCR fragments used to compile the complete TbCLH open reading frame are
depicted below. Thin lines represent the locations of sheared genomic DNA end
sequences and the broken line represents the end sequence of a BAC genomic DNA
clone. Accession numbers are shown alongside each sequence. Thick lines
represent the locations of the PCR fragments. (B) The
ß-adaptin/ß-arrestin and light chain binding sites of TbCLH are
conserved. The upper alignment of human, yeast and trypanosomal clathrin heavy
chain shows the high degree of conservation within the ß-adaptin and
ß-arrestin binding site. The residues Q89, F91, K96 and K98 critical for
arrestin binding by human clathrin heavy chain are conserved. The lower
alignment shows the conservation of residues involved in light chain binding.
Large arrows indicate residues involved in trimerisation and light chain
binding; small arrows indicate residues preferentially involved in light chain
binding. Identical residues are boxed, conservative mutations are shaded. (C)
Schematic representation of the domain structure of human ß1-adaptin and
TbAPß1. Higher eukaryotic ß-adaptins are comprised of a 60-70 kDa
trunk domain separated from a 25-30 kDa appendage domain by a 
100 residue
linker. The appendage domain is absent in the TbAPß1 sequence. The
binding sites for arrestins, clathrin heavy chain (CHC), AP180, epsin and
eps15 in higher eukaryotic ß-adaptin are illustrated. Also shown is a
putative clathrin binding box sequence in TbAPß1. Trypanosomal and yeast
ß1-adaptins terminate with a sequence similar to clathrin binding
sequences located in the hinge region of human ß-adaptins
(HuAPß1,2,3) and the C-termini of a yeast epsin homologue (ScEnt) and
yeast AP180 (ScAP180). The highly conserved leucine and aspartate residues are
boxed.
