Lens Major Intrinsic Protein (MIP) Promotes Adhesion When Reconstituted into Large Unilamellar Liposomes
Author
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Michea Acevedo, Luis
Author
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Fuente Vera, Milton de la
es_CL
Author
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Lagos Wilson, Néstor
es_CL
Admission date
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2014-01-10T15:28:34Z
Available date
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2014-01-10T15:28:34Z
Publication date
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1994
Cita de ítem
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Biochemistry, Vol. 33, No. 24, 1994, 7663-7669
en_US
Identifier
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https://repositorio.uchile.cl/handle/2250/129132
Abstract
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The vertebrate lens behaves like a syncytium, and it is formed mainly by cells called lens fibers.
Between the fibers are extensive networks of membrane junctions. The major intrinsic protein (MIP)
constitutes about 50-60% of the intrinsic membrane proteins found in lens fiber junctions. The role of MIP
is unknown. Nevertheless, it has been proposed that it is the protein responsible for the adhesion between
the plasmatic membranes of the lens fibers. The aim of our studies was to test the adhesion-promoting role
of MIP. We reconstituted MIP into large unilamellar vesicles (LUV) of phosphatidylcholine (PC) and
studied the vesicle aggregation between MIP-reconstituted LUV (PC-MIP) and phosphatidylserine (PS)
vesicles. The aggregation process was monitored using methods based on resonance energy transfer (RET)
and turbidity measurements. Neither RET nor an increase in turbidity occurred in any combination except
in the presence of both MIP and PS. The liposomes thus aggregate through protein-lipid interactions.
These results show that MIP promotes adhesion with negatively charged membranes, indicating that the
adhesion is electrostatic in nature. Aggregation was fastest a t pH 6.0. The aggregation effect was abolished
with pronase treatment. Preincubation of PC-MIP vesicles with anti-MIP polyclonal serum also inhibited
the aggregation. These studies are the first experimental evidence supporting the hypothesis of an adhesive
role for MIP.
en_US
Patrocinador
dc.description.sponsorship
This investigation was supported by FONDECYT 1096-91, DTI B
3245-9015,and FONDECYT 1930988. L.M. wassupported by adoctoral
fellowship from CONICYT, FONDECYT 2930001, and Universidad de Chile