Gene array and expression of mouse retina guanylate cyclase activating proteins 1 and 2.
OBJECTIVE
To identify gene arrangement, chromosomal localization, and expression pattern of mouse guanylate cyclase activating proteins GCAP1 and GCAP2, retina-specific Ca2+-binding proteins, and photoreceptor guanylate cyclase activators.


METHODS
The GCAP1 and GCAP2 genes were cloned from genomic libraries and sequenced. The chromosomal localization of the GCAP array was determined using fluorescent in situ hybridization. The expression of GCAP1 and GCAP2 in mouse retinal tissue was determined by immunocytochemistry.


RESULTS
In this study, the mouse GCAP1 and GCAP2 gene array, its chromosomal localization, RNA transcripts, and immunolocalization of the gene products were fully characterized. The GCAP tail-to-tail array is located at the D band of chromosome 17. Each gene is transcribed into a single transcript of 0.8 kb (GCAP1) and 2 kb (GCAP2). Immunocytochemistry showed that both GCAP genes are expressed in retinal photoreceptor cells, but GCAP2 was nearly undetectable in cones. GCAP2 was also found in amacrine and ganglion cells of the inner retina. Light-adapted and dark-adapted retinas showed no significant difference in the distribution of the most intense GCAP2 staining within the outer segment and outer plexiform layers.


CONCLUSIONS
Identical GCAP gene structures and the existence of the tail-to-tail gene array in mouse and human suggest an ancient gene duplication-inversion event preceding mammalian diversification. Identification of both GCAPs in synaptic regions, and of GCAP2 in the inner retina suggest roles of these Ca-binding proteins in addition to regulation of phototransduction.
Howes
K
K
Moran Eye Center, University of Utah Health Science Center, Salt Lake City 84132, USA.
Bronson
J D
JD
Dang
Y L
YL
Li
N
N
Zhang
K
K
Ruiz
C
C
Helekar
B
B
Lee
M
M
Subbaraya
I
I
Kolb
H
H
Chen
J
J
Baehr
W
W
D000221:Adaptation, Ocular; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D002875:Chromosomes / Q000378:metabolism; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D051604:Guanylate Cyclase-Activating Proteins; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D010786:Photoreceptor Cells / Q000201:enzymology*; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000201:enzymology; D012165:Retinal Ganglion Cells / Q000201:enzymology; D017386:Sequence Homology, Amino Acid
D002135:Calcium-Binding Proteins; C496736:GUCA1A protein, human; C496739:GUCA1B protein, human; D051604:Guanylate Cyclase-Activating Proteins; C496737:Guca1a protein, mouse; C496740:Guca1b protein, mouse; D012333:RNA, Messenger