Sequences that represent functional segments

To demonstrate the existence of functional elements responsible for pore properties of channel proteins, peptides with sequences that represent such functional segments are synthesized and their ability to mimic the targeted biological activity is tested by incorporation of the peptides into lipid bilayers. This approach allows rapid determination of which presumed transmembrane helices may form functional channels. The peptides self-assemble in the membrane to generate conductive oligomers, presumably with hydrophobic surfaces that face the phospholipid and hydrophilic residues that fine the pore. Channels of different sizes (oligomeric number) result (37, 48). 

Fig. 4. Comparison of Mad and Mad orthologues from Podospora anserina (Grisea) and Schizosaccharomyces pom.be (Cufl). All contain a conserved N-terminal 40-residue Zn(II) module that constitutes part of the DNA-hinding interface. Two Cys-rich motifs in the C-terminal segment of Mad, designated Cl and C2, are conserved in Grisea and Cufl. The Cl and C2 motifs are part of transactivation domains. The Cl motif is a functional Cu-regulatory domain in Mad. The sequence of the Cl motif is shown at the top. The dark ovals represent the positions of cysteinyl residues in each molecule. Each Cys-rich motif in Mad hinds four Cu(l) ions.

Fig. 2. The location of silent mutations within Vn and VK segments. The position of silent nucleotide substitutions that have been observed in the functionally rearranged V genes expressed by hybridomas derived from immunized mice are indicated by an asterisk. Identity with the germ-line (or consensus) sequence is indicated by a dash. The location of complementarity determining regions (CDR) is indicated. The Vnll data represent the compilation of 3 independent Vn sequences, the VnOxl sequence represents 8 Vn sequences and the VKOxl sequence represents 5 sequences. (The VH11 data are taken from [93] and the VHOxl and V Oxl data are taken from references [100] and [101].)...

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