GRIFIN, a novel lens-specific protein related to the galectin family.
The vertebrate lens is a relatively simple cellular structure that has evolved to refract light. The ability of the lens to focus light on the retina derives from a number of properties including the expression at high levels of a selection of soluble proteins referred to as the crystallins. In the present study, we have used differential cDNA display techniques to identify a novel, highly abundant and soluble lens protein. Though related to the family of soluble lectins called galectins, it does not bind beta-galactoside sugars and has atypical sequences at normally conserved regions of the carbohydrate-binding domain. Like some galectin family members, it can form a stable dimer. It is expressed only in the lens and is located at the interface between lens fiber cells despite the apparent lack of any membrane-targeting motifs. This protein is designated GRIFIN (galectin-related inter-fiber protein) to reflect its exclusion from the galectin family given the lack of affinity for beta-galactosides. Although the abundance, solubility, and lens-specific expression of GRIFIN would argue that it represents a new crystallin, its location at the fiber cell interface might suggest that its primary function is executed at the membrane.
Ogden
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AT
Skirball Institute for Biomolecular Medicine, New York University Medical Center, New York, New York 10016, USA.
Nunes
I
I
Ko
K
K
Wu
S
S
Hines
C S
CS
Wang
A F
AF
Hegde
R S
RS
Lang
R A
RA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary; D019281:Dimerization; D005136:Eye Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D037161:Galectins; D006388:Hemagglutinins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D007785:Lactose / Q000378:metabolism; D007908:Lens, Crystalline / Q000378:metabolism*; D008969:Molecular Sequence Data; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D005136:Eye Proteins; C115484:GRIFIN protein, rat; D037161:Galectins; C485455:Grifin protein, mouse; D006388:Hemagglutinins; D012333:RNA, Messenger; D007785:Lactose