Major intrinsic polypeptide (MIP26K) from human lens membrane: characterization of low-molecular-weight forms in the aging human lens.
Antisera made against a C-terminal octapeptide of bovine MIP26K and against an N-terminal nonapeptide from the same protein have been used to determine the location of age-dependent cleavage sites of MIP26K in the human lens. Neither the C-terminal antiserum (anti-MIP26K256-263) nor the N-terminal antiserum (anti-MIP26K1-9) binds to the 22,000 MW form of MIP26K, suggesting cleavage from both the N- and C-terminus during lens aging. Anti-MIP26K256-263, but not anti-MIP26K1-9, binds to 20,000 and 15,000 MW forms of MIP26K, demonstrating that age-dependent production of these forms occurs by cleavage from the N-terminal side of the molecule. Together, these results show that age-dependent processing of MIP26K in the human lens occurs from both ends of the molecule, with cleavage from the N-terminal end being mainly responsible for production of the lower-molecular-weight 20,000 and 15,000 MW components.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D020346:Aquaporins; D002648:Child; D002675:Child, Preschool; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000378:metabolism*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007908:Lens, Crystalline / Q000378:metabolism*; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism*; D008875:Middle Aged; D008970:Molecular Weight; D010446:Peptide Fragments / Q000378:metabolism
D020346:Aquaporins; D005136:Eye Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010446:Peptide Fragments; C030328:aquaporin 0