title: Sequence analysis of peptide fragments from the intrinsic membrane protein of calf lens fibers MP26 and its natural maturation product MP22.
abstract: Calf lens fiber plasma membranes, containing only the intrinsic membrane protein MP26 and its maturation product MP22 were treated with proteolytic enzymes such as trypsin, protease V8 from S. aureus or with chemical agents as CNBr in formic acid. The cleavage products, purified by electrophoresis, were analysed for their amino acid composition and N-terminal sequences. Proteolysis gave rise to peptides which were mainly shortened at the C-terminal end of the molecules. While the V8 protease produced a fragment with a similar N-terminal sequence as the maturation product MP22, trypsin yielded another cleavage product. Chemical hydrolysis yielded large fragments (11-15 kDa) with hydrophobic N-terminal sequences. Our results suggest that MP26 is characterised by an N-terminal signal sequence and possesses other hydrophobic domains which could function as untranslocated insertion sequences.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020346:Aquaporins; D002417:Cattle; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism; D005136:Eye Proteins / Q000032:analysis*; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000032:analysis*; D008666:Metalloendopeptidases; D010446:Peptide Fragments / Q000032:analysis*; D014357:Trypsin / Q000378:metabolism
chemical_list: D020346:Aquaporins; D005136:Eye Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010446:Peptide Fragments; C030328:aquaporin 0; D010450:Endopeptidases; D014357:Trypsin; D008666:Metalloendopeptidases; C022653:auR protein, Staphylococcus aureus