The mouse S‐antigen gene

Abstract

We have characterized a gene for mouse S-antigen and compared its sequence with that of corresponding human and two recently published Drosophila S-antigen genes. The mouse S-antigen gene was approximately 50 kbp in length and consisted of 16 exons and 15 introns. The length of most exons was less than 100 bp and the smallest one was only 10 bp. In contrast, the length of most introns was larger than 2 kbp and the gene consisted of 97% intron and 3% exon. Both splice sites for donor and accepter were in good agreement with the GT/AG rule. S-antigen genes in human and mouse were highly conserved. In contrast, genes for the Drosophila 49-kDa arrestin homolog and arrestin consist of three introns and four exons and two introns and three exons, respectively. The 5'-flanking region of the mouse S-antigen gene, approximately 1.0 kbp long, had no regulatory elements for transcription such as the TATA, CAAT and GC boxes, while a Drosophifu arrestin gene has TATA and CAAT boxes. Interestingly, the 5'-flanking region of the mouse gene had promoter activity in an in vitro transcription assay using a nuclear extract of rat brain. A major transcription start site was found at 387 bp upstream from the translation start codon ATG in mouse. From our results, and those of others, we suggest that the S-antigen gene has evolved from a coinman ancestor gene by either insertion or deletion of introns. Such an alteration of gene structure may have played a role in the evolution of the S-antigen.Phototransduction, which converts light energy into neuronal impulse, takes place in the photoreceptor cells of the retina. Initially, light activates rhodopsin, the photoactivated rhodopsin then interacts with transducin, which in turn activates cGMP phosphodiesterase which then hydrolyzes cGMP. The decrease in intracellular concentration of cGMP modulates the influx of Na' ions through plasma-membrane channels and initiates membrane hyperpolarization [I, 21. Shortly after light activation, rhodopsin is phosphorylated by rhodopsin kinase and this modification is thought to be involved in deactivation of phototransduction [3, 41. In contrast to the mammalian system, Drosophila phototransduction differs from that of vertebrates. Phospholipase C, instead of phosphodiesterase, catalyzes the hydrolysis of phosphatidyl inositol 4,5-bisphosphate to inositol trisphosphate [5].One of the major soluble proteins in photoreceptor cells, S-antigen, has been well characterized [6]. This protein is also referred to as 48-kDa protein or arrestin [4,7, 81 and is known to have an inhibitory role in the activated phototransduction cascade [3,8]. Although the exact mechanism of the inhibition is unknown, it is postulated that S-antigen binds to photoexcited, phosphorylated rhodopsin and quenches the activation of light-dependent cGMP phosphodiesterase [3, 7, 9, Corre.~pondencc to

Immediate Upstream Sequence of Arrestin Directs Rod-specific Expression in Xenopus

“…Analysis of genomic structure showed that the structural organization at the 5Ј end of Xenopus rod arrestin is conserved with mouse and human arrestin genes (56,58). However, sequences in the immediate upstream region of the Xenopus rod arrestin gene do not exhibit significant overall homology with conserved mammalian upstream regions, in contrast to that observed for opsins (43).…”

“…4A). There is no apparent TATA motif in the upstream sequence, consistent with other arrestin genes (58,56) and with Xenopus rhodopsin (43) and transducin ␣-subunit 2 genes. However, a TATA-like sequence (ATATT) located at Ϫ25 could potentially function as a TATA-binding protein site (Fig.…”

Immediate Upstream Sequence of Arrestin Directs Rod-specific Expression in Xenopus

“…Analysis of genomic structure showed that the structural organization at the 5Ј end of Xenopus rod arrestin is conserved with mouse and human arrestin genes (56,58). However, sequences in the immediate upstream region of the Xenopus rod arrestin gene do not exhibit significant overall homology with conserved mammalian upstream regions, in contrast to that observed for opsins (43).…”

“…4A). There is no apparent TATA motif in the upstream sequence, consistent with other arrestin genes (58,56) and with Xenopus rhodopsin (43) and transducin ␣-subunit 2 genes. However, a TATA-like sequence (ATATT) located at Ϫ25 could potentially function as a TATA-binding protein site (Fig.…”

The arrestin superfamily: cone arrestins are a fourth family

“…3. Deduced amino acid sequences of 18 arrestin proteins aligned by CLUSTAL V. Human S-antigen (HU SAG) [13], rat S-antigen (RAT SAG) [14,5], mouse S-antigen (MUS SAG) [15], bovine S-antigen (BOV SAG) [16], humanfl-arrestinl (HU BAR1) [17], rat fl-arrestinl (RAT BAR1) [17,5], bovine fl-arrestin 1 (BOV BAR 1) [19], human fl-arrestin2 (HU BAR2) [20], rat fl-arrestin2 (RAT BAR2) [18,2], bovine fl-arrestin2 (BOV BAR2) [21], human cone arrestin (HU CAR) [1,2], Drosophila melanogaster arrestin I (D. mel I) [22,23], Drosophila melanogaster arrestin II (D. mel II) [24,25], Drosophila miranda arrestin (D. miranda) [26], Limulus arrestin (LIM) [27], Loeusta arrestin (LOCUST) [28], and Heliothis arrestin (Heliothis) [28]. Gaps (-) were introduced to obtain maximum similarity.…”

Splice Variants of Arrestins

“…Nucleotide numbering begins with the deoxyadenosine in the initiating ' ATG ' ; amino acid numbering begins with the initiating methionine. Arrows and numbers above the sequence indicate the 3h boundaries of each known exon (Tsuda et al, 1991). An alternative exon not used in mouse arrestin is used in mARR∆13-16 to complete the 3h-untranslated region of this variant.…”

“…Known splice variants of the retinal arrestins. The upper diagram shows the arrestin gene structure (modified from Tsuda et al, 1991), in which the coding region of the arrestin mRNA is contained in exons 2-16. Shown below the gene structure are diagrams of the coding region of the five known forms of arrestin : bArr [bovine arrestin ; amino acid numbering is indicated below the diagram] ; bArr∆16 [l p44 ; variant of bovine arrestin with exon 16 spliced out ; shaded box shows another exon that must be present in the arrestin gene to complete the variant's mRNA ; identified in ROS (Smith et al, 1994)] ; hArr∆12 [variant of human arrestin with exon 12 spliced out ; identified in the retina (Smith, 1996)] ; mArr∆13-16 [variant of mouse arrestin with exons 13-16 spliced out ; shaded box shows alternative exon used to complete the mRNA ; identified in the retina (this study) ; hArr∆13 [splice variant of human arrestin missing exon 13 ; identified in peripheral blood leukocytes (Parruti et al, 1993)].…”

Immediate Upstream Sequence of Arrestin Directs Rod-specific Expression in Xenopus

“…Analysis of genomic structure showed that the structural organization at the 5Ј end of Xenopus rod arrestin is conserved with mouse and human arrestin genes (56,58). However, sequences in the immediate upstream region of the Xenopus rod arrestin gene do not exhibit significant overall homology with conserved mammalian upstream regions, in contrast to that observed for opsins (43).…”

“…4A). There is no apparent TATA motif in the upstream sequence, consistent with other arrestin genes (58,56) and with Xenopus rhodopsin (43) and transducin ␣-subunit 2 genes. However, a TATA-like sequence (ATATT) located at Ϫ25 could potentially function as a TATA-binding protein site (Fig.…”

The arrestin superfamily: cone arrestins are a fourth family

“…3. Deduced amino acid sequences of 18 arrestin proteins aligned by CLUSTAL V. Human S-antigen (HU SAG) [13], rat S-antigen (RAT SAG) [14,5], mouse S-antigen (MUS SAG) [15], bovine S-antigen (BOV SAG) [16], humanfl-arrestinl (HU BAR1) [17], rat fl-arrestinl (RAT BAR1) [17,5], bovine fl-arrestin 1 (BOV BAR 1) [19], human fl-arrestin2 (HU BAR2) [20], rat fl-arrestin2 (RAT BAR2) [18,2], bovine fl-arrestin2 (BOV BAR2) [21], human cone arrestin (HU CAR) [1,2], Drosophila melanogaster arrestin I (D. mel I) [22,23], Drosophila melanogaster arrestin II (D. mel II) [24,25], Drosophila miranda arrestin (D. miranda) [26], Limulus arrestin (LIM) [27], Loeusta arrestin (LOCUST) [28], and Heliothis arrestin (Heliothis) [28]. Gaps (-) were introduced to obtain maximum similarity.…”

Splice Variants of Arrestins

“…Nucleotide numbering begins with the deoxyadenosine in the initiating ' ATG ' ; amino acid numbering begins with the initiating methionine. Arrows and numbers above the sequence indicate the 3h boundaries of each known exon (Tsuda et al, 1991). An alternative exon not used in mouse arrestin is used in mARR∆13-16 to complete the 3h-untranslated region of this variant.…”

“…Known splice variants of the retinal arrestins. The upper diagram shows the arrestin gene structure (modified from Tsuda et al, 1991), in which the coding region of the arrestin mRNA is contained in exons 2-16. Shown below the gene structure are diagrams of the coding region of the five known forms of arrestin : bArr [bovine arrestin ; amino acid numbering is indicated below the diagram] ; bArr∆16 [l p44 ; variant of bovine arrestin with exon 16 spliced out ; shaded box shows another exon that must be present in the arrestin gene to complete the variant's mRNA ; identified in ROS (Smith et al, 1994)] ; hArr∆12 [variant of human arrestin with exon 12 spliced out ; identified in the retina (Smith, 1996)] ; mArr∆13-16 [variant of mouse arrestin with exons 13-16 spliced out ; shaded box shows alternative exon used to complete the mRNA ; identified in the retina (this study) ; hArr∆13 [splice variant of human arrestin missing exon 13 ; identified in peripheral blood leukocytes (Parruti et al, 1993)].…”

Immediate Upstream Sequence of Arrestin Directs Rod-specific Expression in Xenopus

“…Analysis of genomic structure showed that the structural organization at the 5Ј end of Xenopus rod arrestin is conserved with mouse and human arrestin genes (56,58). However, sequences in the immediate upstream region of the Xenopus rod arrestin gene do not exhibit significant overall homology with conserved mammalian upstream regions, in contrast to that observed for opsins (43).…”

“…4A). There is no apparent TATA motif in the upstream sequence, consistent with other arrestin genes (58,56) and with Xenopus rhodopsin (43) and transducin ␣-subunit 2 genes. However, a TATA-like sequence (ATATT) located at Ϫ25 could potentially function as a TATA-binding protein site (Fig.…”

The arrestin superfamily: cone arrestins are a fourth family

“…3. Deduced amino acid sequences of 18 arrestin proteins aligned by CLUSTAL V. Human S-antigen (HU SAG) [13], rat S-antigen (RAT SAG) [14,5], mouse S-antigen (MUS SAG) [15], bovine S-antigen (BOV SAG) [16], humanfl-arrestinl (HU BAR1) [17], rat fl-arrestinl (RAT BAR1) [17,5], bovine fl-arrestin 1 (BOV BAR 1) [19], human fl-arrestin2 (HU BAR2) [20], rat fl-arrestin2 (RAT BAR2) [18,2], bovine fl-arrestin2 (BOV BAR2) [21], human cone arrestin (HU CAR) [1,2], Drosophila melanogaster arrestin I (D. mel I) [22,23], Drosophila melanogaster arrestin II (D. mel II) [24,25], Drosophila miranda arrestin (D. miranda) [26], Limulus arrestin (LIM) [27], Loeusta arrestin (LOCUST) [28], and Heliothis arrestin (Heliothis) [28]. Gaps (-) were introduced to obtain maximum similarity.…”

Splice Variants of Arrestins

“…Nucleotide numbering begins with the deoxyadenosine in the initiating ' ATG ' ; amino acid numbering begins with the initiating methionine. Arrows and numbers above the sequence indicate the 3h boundaries of each known exon (Tsuda et al, 1991). An alternative exon not used in mouse arrestin is used in mARR∆13-16 to complete the 3h-untranslated region of this variant.…”

“…Known splice variants of the retinal arrestins. The upper diagram shows the arrestin gene structure (modified from Tsuda et al, 1991), in which the coding region of the arrestin mRNA is contained in exons 2-16. Shown below the gene structure are diagrams of the coding region of the five known forms of arrestin : bArr [bovine arrestin ; amino acid numbering is indicated below the diagram] ; bArr∆16 [l p44 ; variant of bovine arrestin with exon 16 spliced out ; shaded box shows another exon that must be present in the arrestin gene to complete the variant's mRNA ; identified in ROS (Smith et al, 1994)] ; hArr∆12 [variant of human arrestin with exon 12 spliced out ; identified in the retina (Smith, 1996)] ; mArr∆13-16 [variant of mouse arrestin with exons 13-16 spliced out ; shaded box shows alternative exon used to complete the mRNA ; identified in the retina (this study) ; hArr∆13 [splice variant of human arrestin missing exon 13 ; identified in peripheral blood leukocytes (Parruti et al, 1993)].…”