A Retinaldehyde Dehydrogenase as a Structural Protein in a Mammalian Eye Lens

doi:10.1074/jbc.271.26.15623

A Retinaldehyde Dehydrogenase as a Structural Protein in a Mammalian Eye Lens

GENE RECRUITMENT OF η-CRYSTALLIN*

From the Section on Molecular Structure and Function, Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-2730

^‡ To whom correspondence should be addressed:
Chief, Section on Molecular Structure and Function, LMDB, National Eye Institute, Bldg. 6, Rm. 222, National Institutes of Health, Bethesda, MD 20892-2730.
Tel.: 301-402-3452; Fax: 301-496-0078; E-mail: graeme{at}mge2.nei.nih.gov.

Abstract

η-Crystallin is a taxon-specific crystallin, a major component of the eye lens in elephant shrews (Macroscelidea). Sequence analysis of η-crystallin from two genera of elephant shrews and expression of recombinant η-crystallin show that the protein is a cytoplasmic (class 1) aldehyde dehydrogenase (ALDH1, EC) with activity for the oxidation of retinaldehyde to retinoic acid. Unlike many other mammals, elephant shrews have two ALDH1 genes. One encodes ALDH1/η-crystallin which, in addition to its very high expression in lens, is also the predominant form of ALDH1 expressed in other parts of the eye. The second gene encodes a “non-lens” ALDH1 (ALDH1-nl) which is the predominant form expressed in liver. This pattern of tissue preference contrasts with other mammals which make use of the same major ALDH1 transcript in both ocular and non-ocular tissues. Thus the gene recruitment of ALDH1/η-crystallin as a structural protein in elephant shrew lenses is associated with its collateral recruitment as the major form of ALDH1 expressed in other parts of the eye.

Footnotes

↵* The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) U02483[GenBank], U03906[GenBank], and U40486[GenBank].
↵¹ The abbreviations used are:

ALDH

aldehyde dehydrogenase

RA

retinoic acid

RT-PCR

reverse transcriptase polymerase chain reaction

bp

base pair(s)

CDS

coding sequence

RACE

rapid amplification of cDNA ends

nl

non-lens.
↵² C. Graham and G. Wistow, unpublished data.
- Received February 14, 1996.
- Revision received April 2, 1996.