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signal sequencea PEPTIDE of about 15 to 30 AMINO ACIDS at the N-terminus of certain newly synthesized PROTEINS. The peptide can mediate transport of such a protein across the ENDOPLASMIC RETICULUM or CELL MEMBRANE. It is afterwards cleaved from the protein. Leader peptides can be exploited in GENE CLONING in order to export foreign proteins to the exterior of HOST cells.
any of a class of compounds of low molecular weight which yield two or more amino acids on hydrolysis; known as di-, tri-, tetra- etc. peptides, depending on the number of amino acids in the molecule. Peptides form the constituent parts of proteins. See also polypeptide.
a step in the signal hypothesis advanced to explain the mechanisms governing the fate of newly formed polypeptides or secretory proteins.
a pattern of peptide fragments, characteristic of a particular protein. Produced by using either proteolytic enzymes such as trypsin or chemicals such as cyanogen bromide to cut proteins at a relatively small number of particular sites, the peptide fragments are then separated by chromatographic or electrophoretic procedures. Called also fingerprint.
peptide-para-aminobenzoic acid test
see bt-paba test.