Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Stop codon”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,513 records · Page 84Linked to original sources
PubMed1990

Characterization and expression of the cbbE' gene of Coxiella burnetii.

A gene which is unique to the QpRS plasmid from chronic isolates of Coxiella burnetii was cloned, sequenced, and expressed in Escherichia coli. This gene, termed cbbE', codes for a putative surface protein of approximately 55 kDa, termed the E' protein. The cbbE' gene is 1485 bp in length, and is preceded by predicted promoter regulatory sequences of TTTAAT (-35), TATAAT (-10), and a Shine-Dalgarno sequence of GGAGAGA, all of which closely resemble those of E. coli and other rickettsiae. The open reading frame (ORF) of cbbE' ends with a UAA codon followed by a second in-frame UAG stop codon and a region of dyad symmetry which may act as a rho-factor-independent terminator. The ORF of cbbE' is capable of coding for a polypeptide of 495 amino acids with a predicted molecular mass of 55893 Da. The E' protein has a predicted pI of approximately 8.7, and contains a distinct hydrophobic region of 12 amino acid residues. In vitro transcription/translation and E. coli expression of recombinant plasmids containing cbbE' produce a protein of approximately 55 kDa. The in vivo expression of cbbE' yields a novel protein that can be detected on immunoblots developed with rabbit antiserum generated against purified outer membrane from C. burnetii. DNA hybridization analysis shows that cbbE' is unique to the QpRS plasmid found in chronic isolates of C. burnetii, and is absent in chromosomal DNA and plasmids (QpH1, QpDG) from other isolates of C. burnetii. A search of various DNA and amino acid sequence data bases revealed no homologies to cbbE'.

Amino Acid Sequence↗
PubMed2000

A keratin 14 'knockout' mutation in recessive epidermolysis bullosa simplex resulting in less severe disease.

Epidermolysis bullosa simplex (EBS) is a blistering skin disease caused in most cases by mis-sense mutations in genes encoding the basal epidermal keratin (K) 5 and K14. The inheritance is usually autosomal dominant and the mutant keratin proteins appear to exert a dominant negative effect on the keratin intermediate filament cytoskeleton in basal keratinocytes. We report a child with a homozygous K14 mutation resulting in the complete absence of K14 protein in the epidermis; remarkably, he only had mild to moderate disease. Electron microscopy of a skin biopsy showed a marked reduction in numbers of keratin intermediate filaments in the basal keratinocytes. Immunofluorescence microscopy using monoclonal antibody LL001 against K14 showed no staining, suggesting a functional knockout of K14. Sequence analysis of genomic DNA revealed a homozygous mutation in codon 31 of K14 that resulted in a premature stop codon further downstream in exon 1. The child's mother, who is unaffected by the disease, is heterozygous for the mutation. The consanguineous father was unaffected and unavailable for testing. The resulting mRNA is predicted to encode a protein of 116 amino acids, of which the first 30 are identical to the normal K14 sequence, and the remaining 86 residues are mis-sense sequence. Four previously reported cases of autosomal recessive EBS with functional knockout of K14 were severely affected by blistering, in contrast to our patient in whom the predicted protein has only the first 30 amino acids of K14 and is therefore the closest to a true knockout of K14 protein yet identified.

Consanguinity↗
PubMed1998

Promoter characterization and constitutive expression of the Escherichia coli gcvR gene.

The Escherichia coli glycine cleavage repressor protein (GcvR) negatively regulates expression of the glycine cleavage operon (gcv). In this study, the gcvR translational start site was determined by N-terminal amino acid sequence analysis of a GcvR-LacZ fusion protein. Primer extension analysis of the gcvR promoter region identified a primary transcription start site 27 bp upstream of the UUG translation start site and a minor transcription start site approximately 100 bp upstream of the translation start codon. The -10 and -35 promoter regions upstream of the primary transcription start site were defined by mutational analysis. Expression of a gcvR-lacZ fusion was unaltered in the presence of glycine or inosine, molecules known to induce or repress expression of gcv, respectively. In addition, it was shown that gcvR-lacZ expression is neither regulated by the glycine cleavage activator protein (GcvA) nor autogenously regulated by GcvR. From DNA sequence analysis, it was predicted that the translation start codon of the downstream bcp gene overlaps the gcvR stop codon, suggesting that these genes may form an operon. However, a down mutation in the -10 promoter region of gcvR had no effect on the expression of a downstream bcp-lacZ fusion, and primer extension analysis of the bcp promoter region demonstrated that bcp has its own promoter within the gcvR coding sequence. These results show that gcvR and bcp do not form an operon. Furthermore, the deletion of bcp from the chromosome had no effect on gcv-lacZ expression.

Amino Acid Sequence↗
PubMed1998

Generation of a mutant infectious bursal disease virus that does not cause bursal lesions.

A reverse genetics system for birnavirus, based on synthetic transcripts of the infectious bursal disease virus (IBDV) genome, was recently developed (E. Mundt and V. N. Vakharia, Proc. Natl. Acad. Sci. USA 93:11131-11136, 1996). To study the function of the 17-kDa nonstructural (NS) protein in viral growth and pathogenesis, we constructed a cDNA clone of IBDV segment A in which the first and only initiation codon (ATG) of NS protein was mutated to a stop codon (TAG). Transfection of Vero cells with combined transcripts of either modified or unmodified segment A, and with segment B, generated viable IBDV progeny. When chicken embryo fibroblast cells infected with transfectant viruses were analyzed by immunofluorescence assays using NS-specific antiserum, the mutant virus did not yield a fluorescence signal, indicating a lack of NS protein expression. Furthermore, replication kinetics and cytotoxic effects of the mutant virus were compared with those of the parental attenuated vaccine strain of IBDV (D78) in vitro. The mutant virus grew to slightly lower titers than D78 virus and exhibited decreased cytotoxic and apoptotic effects in cell culture. To evaluate the characteristics of the recovered viruses in vivo, we inoculated 3-week-old chickens with D78 or mutant virus and analyzed their bursa for histopathological lesions. The recovered D78 virus caused microscopic lesions and atrophy of the bursa, while the mutant virus failed to induce any pathological lesions or clinical signs of disease. In both instances, the virus was recovered from the bursa, and the presence or absence of mutation in these viruses was confirmed by nucleotide sequence analysis of NS gene. Although the mutant virus exhibited a delay in replication in vivo, it induced levels of IBDV neutralizing antibodies that were similar to those of D78 virus. In addition, no reversion of mutation was detected in the mutant virus recovered from inoculated chickens. These results demonstrate that NS protein is dispensable for viral replication in vitro and in vivo and that it plays an important role in viral pathogenesis. Thus, generation of such NS protein-deficient virus will facilitate the study of immunosuppression and aid in the development of live-attenuated vaccines for IBDV.

Animals↗
PubMed1998

Large number of polymorphic nucleotides and a termination codon in the env gene of the endogenous human retrovirus ERV3.

The terminal portion of the pol gene and the entire env gene of the human endogenous retrovirus ERV3 was screened for polymorphic nucleotides. For this purpose fragments amplified from the desired regions of ERV3 were subjected to single strand conformational analysis (SSCP analysis). Using this approach, we detected 13 polymorphic nucleotides, namely four in the pol gene and nine in the env gene. Three of the nucleotide substitutions were synonymous (not affecting the amino acid code). One of the non-synonymous nucleotide substitutions changed an arginine codon to a termination codon. The alleles at the different polymorphic sites could be arranged into five ERV3 haplotypes, two of which were new. To evaluate the possible significance of the termination codon, which precludes expression of a putative immunoregulatory factor, we examined samples of DNA from patients with multiple sclerosis, a demyelinating disease of presumed autoimmune etiology. We did not find an association between the ERV3 allele with the termination codon and this disease. Perhaps the presence of a stop codon combined with the high number of non-synonymous nucleotide substitutions in the reading frame of the env gene reflects absence of selective constraints during evolution. Obviously, our findings contradict the assumption that the reading frame of the ERV3 env gene has been conserved throughout evolution.

Codon, Terminator↗
PubMed1991

Molecular and metabolic basis for the metabolic disorder normotriglyceridemic abetalipoproteinemia.

We have previously described a disorder, normotriglyceridemic abetalipoproteinemia, that is characterized by the virtual absence of plasma low density lipoproteins and complete absence of apoB-100, but with apparently normal secretion of triglyceride-rich lipoproteins containing apoB-48. The patient's plasma lipoproteins were shown on polyacrylamide gels and by antibody mapping to have a new truncated apoB variant, apoB-50, circulating along with her apoB-48. We have found this individual to be homozygous for a single C-to-T nucleotide substitution at apoB codon 2252, which produces a premature in-frame stop codon. Thus, this is a rare example of homozygous hypobetalipoproteinemia. Electron photomicrographs revealed that the diameters of particles in the d less than 1.006 g/ml lipoprotein fraction, in both the postprandial and postabsorptive state, are bimodally distributed. The molar ratio of apoE to apoB in these particles is 3.5:1, similar to normal VLDL. The plasma LDL interval contains both spherical and cuboidal particles. Autologous reinfusion of labeled d less than 1.006 g/ml lipoproteins showed exponential disappearance from plasma, with an apparent half-removal time of 50 min, somewhat slower than for normal chylomicrons but within the normal range for VLDL. The calculated production rate for apoB was within the normal range in this subject. A very small amount of label was found briefly in the IDL fraction, but none at any time in LDL or HDL. Therefore, because LDL particles that contain apoB-50 lack the putative ligand domain of the LDL receptor, we conclude that the very low level of LDL is due to the rapid removal of the abnormal VLDL particles before their conversion to LDL can take place.

Abetalipoproteinemia↗
PubMed1994

Mutations of the adenomatous polyposis coli gene in sporadic thyroid neoplasms.

Several epidemiological studies have demonstrated an association between familial adenomatous polyposis coli (FAP) and thyroid neoplasms. Predisposition to FAP is conferred by mutations in the APC gene, located on chromosome 5q21. Somatic mutations of APC are also observed in about 60% of sporadic colorectal adenomas and carcinomas, suggesting that disruption of this putative tumor suppressor gene may play a role in both familial as well as acquired colorectal tumorigenesis. The APC gene is expressed in normal human thyroid, thyroid adenomas, and differentiated carcinoma tissues as well as in four clonal human thyroid carcinoma cell lines, as demonstrated by reverse transcriptase-polymerase chain reaction of a 388-base APC messenger ribonucleic acid fragment spanning exons 14 and 15, followed by hybridization to an exon 15-specific complementary DNA probe. Eighty human thyroid neoplasms were examined for loss of heterozygosity of the APC locus, using primers flanking a hypervariable dinucleotide (CA) repeat (CB26) immediately adjacent to the APC gene. Of 71% informative samples, 2 showed allelic loss: a follicular adenoma (FA) and a nodule from a multinodular goiter (MNG). The DNA of 83 benign and malignant thyroid neoplasms and 4 thyroid carcinoma cell lines was examined for mutations within a 1200-basepair stretch of exon 15 by single strand conformation polymorphism. Five sets of overlapping primers were used for PCR. The anaplastic thyroid carcinoma cell line (ARO) had 1 APC allele with an adenine insertion at codon 1556 (ACTA to AACTA), leading to a premature stop codon at 1558. An anaplastic carcinoma had a mutation of codon 1346 (TCA-CCA; Ser to Pro). In summary, the APC gene is expressed in normal and neoplastic human thyroid tissue and is a target for inactivating mutations in some thyroid tumors.

Adenoma↗
PubMed1996

A new compound heterozygous frameshift mutation in the type II 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) gene causes salt-wasting 3 beta-HSD deficiency congenital adrenal hyperplasia.

We report a new compound heterozygous frameshift mutation in the type II 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) gene in a Pakistanian female child with the salt-wasting form of 3 beta-HSD deficiency congenital adrenal hyperplasia. The child, born with clitoral enlargement, manifesting salt-wasting adrenal crisis, and public hair growth during infancy, was treated with hormonal replacement therapy. The etiology of her congenital adrenal hyperplasia, however, was not defined. Two of her siblings, as well as one paternal cousin with ambiguous genitalia and palpable gonads and another paternal cousin with normal female genitalia, had symptoms of adrenal crisis and died during early infancy. Thus, although the family history suggested possible 3 beta-HSD deficiency disorder, suppressed adrenal function caused by excess glucocorticoid therapy in this child at 7 yr of age did not allow hormonal diagnosis. To confirm 3 beta-HSD deficiency, we sequenced the type II 3 beta-HSD gene in the patient, her family, and the parents of her decreased paternal cousins. The type II 3 beta-HSD gene region of a putative promoter, exons I, II, III, and IV, and exon-intron boundaries were amplified by PCR and sequenced in all subjects. The DNA sequence of the child revealed a single nucleotide deletion at codon 318 [ACA (Thr)-->AA] in exon IV in one allele, and two nucleotide deletions at codon 273 [AAA(Lys)-->A] in exon IV in the other allele. The remaining gene sequences were normal. The codon 318 mutation was found in one allele from the father, brother, and parents of the deceased paternal cousins. The codon 273 mutation was found in one allele of the mother and a sister. These findings confirmed inherited 3 beta-HSD deficiency in the child caused by the compound heterozygous type II 3 beta-HSD gene mutation. Both codon 273 and 318 mutations yielding frameshift and premature stop codons at codons 279 and 367, respectively, are predicted to result in an altered and truncated type II 3 beta-HSD protein, thereby causing salt-wasting 3 beta-HSD deficiency in the patient. The type II 3 beta-HSD gene findings and clinical history of her family members suggest that the patient's deceased siblings were likely affected males with the same compound heterozygous mutations of the gene as in the proband, whereas the deceased cousins were likely affected with the homozygous codon 318 mutation in the gene.

3-Hydroxysteroid Dehydrogenases↗
PubMed1999

Complete androgen insensitivity caused by a new frameshift deletion of two base pairs in exon 1 of the human androgen receptor gene.

We describe a novel mutation in exon 1 of the androgen receptor gene in a patient with complete androgen insensitivity (CAIS). Endocrine findings were typical for androgen insensitivity (testosterone serum levels in the upper limit of normal males and increased LH serum concentrations). Biochemical investigations in cultured genital skin fibroblasts of the patient showed a normal 5alpha-reductase activity but a complete absence of androgen binding. Western blot analysis revealed no detectable protein product. Sequence analysis of the entire coding region of the androgen receptor gene resulted in the identification of a 2-bp deletion in codon 472, causing frameshift and introduction of a premature stop codon 27 codons downstream of the mutation.

Adult↗
PubMedDate not supplied

Recurrence of a nonsense mutation in the conserved domain of SRY in a Brazilian patient with 46,XY gonadal dysgenesis.

We tested a female patient with 46,XY karyotype and pure gonadal dysgenesis for the presence of the SRY gene and for mutations within the SRY conserved domain. A point mutation was identified at nucleotide position 209 with respect to the first ATG. The base substitution is a G-->A transition in the first nucleotide of codon 70 which changes a tryptophan (TGG) to a stop codon (TAG). Even though the father was not available for investigation we assumed that it is a de novo mutation, since it probably generates a nonfunctional truncated protein.

Adolescent↗
PubMed1996

An improved diagnostic test for rod cone dysplasia 1 (rcd1) using allele-specific polymerase chain reaction.

PURPOSE: To develop an improved diagnostic test for rod-cone dysplasia type 1 (rcd1). The rcd1 phenotype is an early onset, autosomal recessive disease caused by a mutation in the canine rod cyclic GMP phosphodiesterase beta-subunit (PDE6B) gene. A G to A transition in codon 807 at nucleotide position 2420 results in a stop codon. This is the only disease causing mutation detected so far in the canine PDE6B gene. METHODS: Allele specific primers were designed in which the 3 end had the nucleotide corresponding to either the wild type or the mutant rcd1 allele. PCR was done using the allele specific primers in combination with a common primer complementary to the opposite strand to distinguish between the wild type and the rcd1 alleles. RESULTS: The wild type and rcd1 alleles were identified successfully in two independent ASPCRs done with two different sets of allele specific primers. Further, both alleles could be amplified in a single tube and distinguished based on the size difference of the PCR products using one allele specific primer of altered length by the addition of a 9 nucleotide long linker. CONCLUSIONS: We have developed an improved diagnostic test for the disease based on ASPCR such that the presence or absence of different size amplified fragments provides direct determination of the genotype. In contrast to previously reported diagnostic tests, this method is more efficient because it eliminates the need for any further manipulation of the PCR product.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2001

Characterization of the human alpha-synuclein gene: Genomic structure, transcription start site, promoter region and polymorphisms.

The human NACP/alpha-synuclein gene has been cloned. This gene consists of 6 exons ranging in size from 42 to 1110 bp. The translation start codon ATG is encoded by exon 2 and the stop codon TAA is encoded by exon 6. The non-Abeta component of Alzheimer's disease amyloid (NAC) is encoded by exon 4. The two previously reported minor isoforms of NACP/alpha-synuclein, NACP112 [29] and NACP126 [6], are alternatively spliced products, in which exon 5 and exon 3 are spliced out, respectively. Exon 1 was found to have different splicing sites, producing different 5'-untranslated sequences in the cDNAs. A previously reported dinucleotide repeat polymorphic marker has been mapped to 8kb upstream of the transcription start site. A highly TC-rich sequence in intron 4 was found to be polymorphic by length and four alleles, A0, A1, A2 and B have been identified in the Caucasian population. Genotyping this polymorphism among pure Alzheimer's, Lewy body variant and Parkinson's subjects and aged normal control subjects did not reveal any significant differences.

Journal Article↗
PubMed2000

Detection of point mutations in promoter and coding sequence of p21 gene in a variety of human malignancies.

OBJECTIVE: p21 is a general inhibitor of cyclin-dependent kinases which leads cells through restriction point of cell cycle. Since p21 has been identified to be a mediator of p53 tumor suppressor activity and directly up-regulated by p53, this study was designed to investigate whether mutations in promoter or coding sequence of p21 were associated with development or progress of tumor. METHODS: A 2.4kb DNA fragment, containing essential promoter, was amplified and sequenced. Furthermore, 346 DNA samples from 9 different types of primary tumors were examined for point mutations in promoter and coding sequence of p21 gene by using SSCP analysis and direct sequencing. RESULTS: Heterozygous or homozygous G to A transition at 5bp upstream and C to A transversion at 160bp downstream of p53 binding site were found. A 44bp heterozygous deletion was detected in a bladder cancer, which started at codon 34 and resulted in frameshift and a premature stop codon downstream. The most abundant variants in coding sequence of p21 gene were a C to A transversion at codon 31 which resulted in Ser to Arg and had been identified being polymorphism. In addition, four rare variants in coding sequence were also found. CONCLUSION: The evidence from this study indicates that mutation in either promoter or coding sequence of p21 gene is rare in a variety of human malignancies.

Cyclin-Dependent Kinase Inhibitor p21↗
PubMed2003

[Analysis of low density lipoprotein receptor function and gene mutation in familial hypercholesterolemic patients].

OBJECTIVE: To investigate low density lipoprotein receptor (LDLR) function and gene mutation in Chinese patients with familial hypercholesterolemia(FH). METHODS: Lymphocytes were isolated from 10 ml anticoagulated peripheral blood of the patients, then a flow-cytometric method (FCM) with 1,1'-dioctadecyl-3,3,3', 3-tetramethylindocarbocyanine perchlorate labelled low density lipoproetin (DiI-LDL) was used to identify the function of LDLR on the surface of lymphocytes. Genomic DNA was isolated from whole blood of FH patients and analyzed by PCR-single strand conformation polymorphism (SSCP) and nucleotide sequencing methods. RESULTS: Defects of binding and uptaking of LDLR were identified by FCM in 2 FH patients in one family, and their parents were examined in the present study. Then they were analyzed genetically. The detected mutation was a deletion of A, which caused a frame shift in codon 297 of exon 6 and introduced a beforehand stop codon in codon 369. CONCLUSION: A novel mutation of LDL receptor gene was detected by the combination of FCM and PCR-SSCP methods.

Adult↗
PubMed1990

Premature translation termination of the pre-E1 alpha subunit of the branched chain alpha-ketoacid dehydrogenase as a cause of maple syrup urine disease in Polled Hereford calves.

Maple syrup urine disease in man and cattle is an inborn metabolic error caused by the deficiency of the branched chain alpha-ketoacid dehydrogenase. We have studied the molecular basis of the disease in Polled Hereford calves. The E1 component of branched chain alpha-ketoacid dehydrogenase was virtually undetectable by Western blot analysis of fibroblasts from an affected calf. Northern blot analysis failed to detect the E1 alpha mRNA species in the fibroblasts. Nevertheless, it was readily demonstrated by reverse transcription of RNA followed by polymerase chain reaction that the mRNA for the E1 alpha subunit was present in the cells, albeit at very low concentrations. Sequencing of the polymerase chain reaction-generated cDNA for the entire coding region of the E1 alpha subunit revealed a single base substitution at codon -6 (CAG to TAG). This mutation introduces a stop codon in the leader peptide of the E1 alpha subunit, resulting in the premature termination of translation. The mutation was verified by hybridization of the amplified cDNA fragments from two affected calves with allele-specific oligonucleotides. This finding explains the pathogenesis of maple syrup urine disease in this breed of cattle, which provides the only known animal model for the human disease. In addition, the results provide evidence for the effect of premature translation termination on reducing the steady-state mRNA level and the dependence of E1 beta protein stability on the co-expression of the E1 alpha.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1989

Ornithine transcarbamylase deficiency resulting from a C-to-T substitution in exon 5 of the ornithine transcarbamylase gene.

To define the molecular basis for the TaqI site alteration in the ornithine transcarbamylase (OTC) (E.C.2.1.3.3) gene of a female patient with mild OTC deficiency, we used a combination of genomic amplification followed by direct sequencing and oligodeoxyribonucleotide hybridization. We obtained evidence for a C-to-T substitution in exon 5 (codon 141) of this gene. This mutation generates a stop codon, in place of Arg, at amino acid 109 of the mature OTC protein. The mutation arose, de novo, in a germ cell of one of the parents.

Adolescent↗
PubMed1995

[Detection of hepatitis B virus by using polymerase chain reaction and nonradioactive DNA probes. I. Identification of mutations in the precore region by PCR-direct sequencing and ASO probe method].

Seroconversion from hepatitis B e antigen (HBeAg) to anti-HBe antibody (anti-HBe) frequently occurs in hosts chronically infected with hepatitis B virus (HBV). Further, this phenomenon is related to a point mutation from guanine to adenine at nucleotide 83 in the precore region of HBV, which, converts codon 28 for tryptophan (TGG:W) to a translational, stop codon (TAG:X). Therefore, we decided to examine HBV in sera from patients for mutations in the precore region by a simple allele-specific oligonucleotide (ASO) probe method. Direct sequencing was first performed on DNA fragments amplified by the polymerase chain reaction in order to establish whether there were mutations in the precore region. Subsequently, specific DNA probes were applied to detection of mutations in the precore region. Subsequently, specific DNA probes were applied to detection of mutations in the precore gene. Five unknown mutations (I10N, C12W, C14S, V17F and A19D), three known mutations (I9V, W28X and G29D) and for novel nucleotide insertions were identified in anti-HBe positive sera. By using seven nonradioactive probes, we could determine the mutations at codons 9, 28 and 29 in anti-HBe positive sera. The W28X mutation was found in anti-HBe positive but not in any of HBeAg positive sera. Meanwhile, wild-type strains of HBV were detectable in sera from patients who were positive to HBeAg or anti-HBe. This ASO probe assay could determine in a few days the mutations in the precore region of HBV, especially including the defect to prohibit the synthesis and secretion of HBeAg.

Amino Acid Sequence↗
PubMed1998

Molecular analysis of the third component of canine complement (C3) and identification of the mutation responsible for hereditary canine C3 deficiency.

Genetically determined deficiency of the third component of complement (C3) in the dog is characterized by a predisposition to recurrent bacterial infections and to type 1 membranoproliferative glomerulonephritis. The current studies were undertaken to characterize the cDNA for wild-type canine C3 and identify the molecular basis for hereditary canine C3 deficiency. Amplification, cloning, and sequence analysis indicated that canine C3 is highly conserved in comparison with human, mouse, and guinea pig C3. Southern blot analysis failed to show any gross deletions or rearrangements of DNA from C3-deficient animals. Northern blot analysis indicated that the livers of these animals contain markedly reduced quantities of a normal length C3 mRNA. The full-length 5.1-kb canine C3 cDNA was amplified in overlapping PCR fragments. Sequence analysis of these fragments has shown a deletion of a cytosine at position 2136 (codon 712), leading to a frameshift that generates a stop codon 11 amino acids downstream. The deletion has been confirmed in genomic DNA, and its inheritance has been demonstrated by allele-specific oligonucleotide hybridization.

Amino Acid Sequence↗