PMID- 10634618
OWN - NLM
STAT- MEDLINE
DCOM- 20000114
LR  - 20071114
IS  - 0146-0404 (Print)
IS  - 0146-0404 (Linking)
VI  - 41
IP  - 1
DP  - 2000 Jan
TI  - Characterization of human lens major intrinsic protein structure.
PG  - 175-82
AB  - PURPOSE: To determine the primary covalent structure of human lens major
      intrinsic protein (MIP) in lenses of varying age. METHODS: MIP was isolated from 
      single human lenses of various ages (7- 86 years) by homogenization of the
      lenses, followed by centrifugation and urea washes of the membranes. Proteins
      present in the membrane preparation were reduced, alkylated, and cleaved by CNBr.
      Peptide fragments were fractionated by reverse-phase high-performance liquid
      chromatography, and the primary structures of the peptides were determined by
      tandem mass spectrometry and Edman sequencing. RESULTS: Complete coverage of the 
      human MIP sequence was observed in the form of CNBr fragments. In addition,
      peptide structures resulting from in vivo heterogeneous N- and C-terminal
      cleavage were characterized. The amount of intact MIP decreased with lens age;
      however, the pattern of truncation did not change from 7 to 86 years. The major
      site of phosphorylation was identified as serine 235. Asparagine residues 246 and
      259 were completely deamidated by age 7 years. CONCLUSIONS: The major structural 
      modifications of human lens MIP have been determined. Human MIP is
      heterogeneously modified in lenses ranging in age from 7 to 86 years of age by N-
      and C-terminal truncation, phosphorylation, and deamidation, resulting in
      decreased levels of native intact MIP with age.
FAU - Schey, K L
AU  - Schey KL
AD  - Department of Cell and Molecular Pharmacology, Medical University of South
      Carolina, Charleston 29425, USA. scheykl@musc.edu
FAU - Little, M
AU  - Little M
FAU - Fowler, J G
AU  - Fowler JG
FAU - Crouch, R K
AU  - Crouch RK
LA  - eng
GR  - EY-10722/EY/NEI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Invest Ophthalmol Vis Sci
JT  - Investigative ophthalmology & visual science
JID - 7703701
RN  - 0 (Aquaporins)
RN  - 0 (Eye Proteins)
RN  - 0 (Membrane Glycoproteins)
RN  - 0 (Peptide Fragments)
RN  - 0 (aquaporin 0)
SB  - IM
MH  - Adolescent
MH  - Adult
MH  - Aged
MH  - Aged, 80 and over
MH  - Aging/physiology
MH  - Amino Acid Sequence
MH  - Aquaporins
MH  - Child
MH  - Chromatography, High Pressure Liquid
MH  - Deamination
MH  - Eye Proteins/*analysis/isolation & purification/metabolism
MH  - Humans
MH  - Lens, Crystalline/*chemistry/metabolism
MH  - *Membrane Glycoproteins
MH  - Middle Aged
MH  - Molecular Sequence Data
MH  - Molecular Weight
MH  - Peptide Fragments/analysis
MH  - Phosphorylation
MH  - Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
EDAT- 2000/01/14 00:00
MHDA- 2000/01/14 00:01
CRDT- 2000/01/14 00:00
PHST- 2000/01/14 00:00 [pubmed]
PHST- 2000/01/14 00:01 [medline]
PHST- 2000/01/14 00:00 [entrez]
PST - ppublish
SO  - Invest Ophthalmol Vis Sci. 2000 Jan;41(1):175-82.