Biomedical subjects

R C Karn

Publications and source records attributed to R C Karn.

At least 19 recordsLinked to original sources

PubMed2001

Female preference for male saliva: implications for sexual isolation of Mus musculus subspecies.

We studied the effects of a single genetic change on a complex mammalian behavior using animals congenic for two variants of Abpa, the gene for the alpha subunit of mouse salivary androgen-binding protein (ABP), in two-way preference tests. Females exhibited a preference for investigating salivas of males of their own genetic type of ABP but not for urines of either type of male. This preference behavior is consistent for samples of mice from geographically diverse populations of Mus musculus domesticus and M. m. musculus. These findings provide an explanation for the observation that this gene is evolving under strong selection.

Androgen-Binding Protein↗

PubMed1999

A comparison of the structures of the alpha:beta and alpha:gamma dimers of mouse salivary androgen-binding protein (ABP) and their differential steroid binding.

Mouse salivary androgen-binding protein (ABP) is a family of dimeric proteins that may play a pheromonal role in Mus musculus. The protein dimer consists of a common alpha subunit disulfide-bonded to a variable (beta or gamma) subunit. Here we report N-terminal sequences of the beta and gamma subunits, showing that they are very similar to each other while being quite different from the alpha subunit. We demonstrate differential androgen binding by the two dimers. Both bind dihydrotestosterone to about the same extent but the alpha:beta dimer binds significantly more testosterone than the alpha:gamma dimer. We discuss the possible significance of this diversity of androgen binding with respect to the possibility that androgen binding is related to a putative pheromonal role for the protein.

Amino Acid Sequence↗

PubMed1999

Reduced nucleotide variability at an androgen-binding protein locus (Abpa) in house mice: evidence for positive natural selection.

Previous work has shown that the gene for the alpha subunit of androgen-binding protein, Abpa, may be involved in premating isolation between different subspecies of the house mouse, Mus musculus. We investigated patterns of DNA sequence variation at Abpa within and between species of mice to test several predictions of a model of neutral molecular evolution. Intraspecific variation among 10 Mus musculus domesticus alleles was compared with divergence between M. m. domesticus and M. caroli for Abpa and two X-linked genes, Glra2 and Amg. No variation was observed at Abpa within M. m. domesticus. The ratio of polymorphism to divergence was significantly lower at Abpa than at Glra2 and Amg, despite the fact that all three genes experience similar rates of recombination. Interspecific comparisons among M. m. domesticus, Mus musculus musculus, Mus musculus castaneus, Mus spretus, Mus spicilegus, and Mus caroli revealed that the ratio of nonsynonymous substitutions to synonymous substitutions on a per-site basis (Ka/Ks) was generally greater than one. The combined observations of no variation at Abpa within M. m: domesticus and uniformly high Ka/Ks values between species suggest that positive directional selection has acted recently at this locus.

Alleles↗

PubMed1998

Steroid binding by mouse salivary proteins.

The goals of this study were to determine the steroid-binding specificity of the mouse salivary androgen-binding protein (ABP) family and to ascertain whether there might be other proteins in mouse saliva capable of binding steroids. The optimal conditions for testosterone binding by mouse salivary proteins were determined using a small-scale chromatography system to separate bound from unbound steroid. Testosterone binding appeared to be biphasic but was directly proportional to saliva concentration, with an optimum temperature of 37 degrees C in the second phase. These results were used to develop a steroid-binding protocol to study the steroid specificity of salivary proteins separated by electrophoresis. The ABP family bound testosterone and progesterone well and HO-progesterone and DHT to a lesser extent but did not bind either cholesterol or estradiol. Steroid structural comparisons suggest that binding by ABP is governed by the A ring of the steroid. Another protein that is not a member of the ABP family bound cholesterol specifically but no protein that specifically bound estradiol was observed.

Androgen-Binding Protein↗

PubMed1994

The mouse salivary androgen-binding protein (ABP) alpha subunit closely resembles chain 1 of the cat allergen Fel dI.

Androgen-binding protein (ABP) is found in the salivas of a wide variety of rodents and it has been proposed that ABP functions in sex and/or subspecies recognition (Karn and Dlouhy, J. Hered. 82, 453, 1991). This is a report of significant identity between the alpha subunit of mouse salivary ABP and Chain 1 of cat allergen Fel dI (50% identity), as well as with two other proteins that share identity with Chain 1 of Fel dI, rabbit uteroglobin (27% identity with ABP alpha) and human lung Clara 10 (27% identity with ABP alpha). The secondary structure predicted for the mouse ABP alpha subunit is a very good fit with the secondary structure determined by X-ray crystallography for rabbit uteroglobin, a protein that shares with mouse ABP the capability of binding steroid. Fel dI is found in cat saliva, sebaceous glands, and pelt. Its function is not known but it has been proposed to be involved in protecting dry epithelia, a parallel to uteroglobin protecting wet epithelia. Since mice, like cats, lick themselves and each other extensively, coating their pelts with ABP may be part of this or another biological function.

Allergens↗

PubMed1993

The amino acid sequence of the alpha subunit of mouse salivary androgen-binding protein (ABP), with a comparison to the partial sequence of the beta subunit and to other ligand-binding proteins.

It has been suggested that three distinct genes, Abpa, Abpb, and Abpg, determine the three subunits of mouse salivary androgen-binding protein (ABP) (Dlouhy, S. R., et al., Genetics 115, 535, 1987). We report the putative amino acid sequence of the subunit common to all forms of ABP, the Alpha subunit, and the partial amino acid sequence of the Beta subunit. These sequences have little in common, supporting the notion of at least two distinct genes coding for the subunits of the most common form of salivary ABP, the A:B dimer. A search of GenBank showed that these sequences have not been reported previously. The Beta subunit shows significant homology with helospectin, a member of the glucagon superfamily, but not enough homology to assign it to the family. No homology exists between ABP subunits and members of the ligand-binding carrier family of proteins nor does ABP show homology with other androgen-binding proteins. Particularly interesting is the observation that there is no relationship to rat prostatic steroid binding protein (PBP), given the similarities in protein tertiary structure, the numbers of subunits and their genes, and the earlier observation of ABP cross-reactive material in mouse prostate.

Amino Acid Sequence↗

PubMed1991

Unique cerebellar phenotype combining granule and Purkinje cell loss: morphological evidence for weaver* pcd double mutant mice.

Weaver (wv/wv) mutant mice lose most granule cells of the cerebellum during the first 2 weeks of postnatal life; 'Purkinje cell degeneration' (pcd/pcd) mutants lose virtually all Purkinje cells between postnatal days 17 and 45. Both these neurological mutations are autosomal recessive. We designed a breeding protocol that, in theory, should result in the production of mice with a doubly mutant, wv/wv*pcd/pcd, genotype. Some of the offspring of such crosses had a novel cerebellar phenotype in which both granule and Purkinje cells underwent degeneration, leading to a highly atrophic cortex. This phenotype is what would be expected in wv/wv*pcd/pcd double mutants, and the proportion of such progeny obtained fits with genetic expectations. We propose that (1) wv/wv*pcd/pcd double mutant mice are viable, and (2) the anatomical phenotype of such mice is a combined expression of the component phenotypes.

Aging↗

PubMed1988

Expression of human salivary protein genes.

Human proline-rich proteins (PRPs) are polymorphic, homologous in sequence, and linked in a cluster called the human salivary protein complex (SPC). Recently this complex was localized to human chromosome band 12p13.2 (Mamula et al., Cytogenet. Cell Genet. 39:279, 1985). We have isolated a PRP cDNA, EO27, from a human parotid gland library, identified it by DNA sequencing, and used it to study the molecular and cellular biology of PRP production. Cell-free translation and mRNA characterization with EO27 indicate that the numerous PRPs seen in saliva are produced from relatively few, large precursors, probably by posttranslational cleavage. This supports an hypothesis originally proposed by Friedman and Karn in 1977 (Am. J. Hum. Genet. 29:44 A; Biochem. Genet. 15:549) and later supported by biochemical studies (Karn et al., Biochem Genet. 17:1061, 1979) and molecular studies (Mamula et al., Fed. Proc. 43:1522, 1984; Maeda et al., J. Biol. Chem. 260:1123, 1985). EO27 was also used in this study to localize PRP mRNA production to the acinar cells of the parotid gland by in situ hybridization.

Amino Acid Sequence↗

PubMed1987

The genes for mouse salivary androgen-binding protein (ABP) subunits alpha and gamma are located on chromosome 7.

We demonstrate that the previously described gene Androgen binding protein (Abp; Dlouhy and Karn, 1984) codes for the Alpha subunit of ABP and rename the locus Androgen binding protein alpha (Abpa). A study of recombinant inbred strains demonstrates that Abpa is located on chromosome 7 near Glucose phosphate isomerase-1 (Gpi-1). Biochemical and genetic evidence indicates the existence of another ABP subunit, Gamma, and its locus, Androgen binding protein gamma (Abpg), that is closely linked to Abpa. Although no polymorphism has yet been found for the previously described Beta subunit of ABP (Dlouhy and Karn, 1983; 1984), we suggest that it represents a third locus. Androgen binding protein beta (Abpb). ABP subunits appear to dimerize randomly and a model is presented demonstrating the origin of six ABP dimers in the salivas of AbpaaAbpga/AbpabAbpgb heterozygous mice. The results of cell-free translation studies in which the pre-ABP subunits are identified specifically by immunoprecipitation with anti-ABP antibody supports the idea that independent mRNAs code for the Alpha, Beta and Gamma subunits.

Androgen-Binding Protein↗

PubMed1987

Identification of a human salivary amylase gene. Partial sequence of genomic DNA suggests a mode of regulation different from that of mouse, Amy1.

We report the identification and partial sequence for a human salivary amylase gene, Amy1. The genomic sequence was compared with known human pancreatic and salivary amylase cDNA sequences and another salivary amylase gene sequence. While most of the intron/exon structure and coding sequences are highly similar to other amylase DNAs, the bulk of the 5' end varies significantly. Major differences in the positions and structures of promoters between human and mouse Amy1 genes suggest that there are important differences between the tissue-specific expressions in the two mammals. Some potential enhancer sequences were identified.

Amino Acid Sequence↗

PubMed1986

Human parotid proline-rich proteins: correlation of genetic polymorphisms to dental caries.

Parotid saliva contains a variety of proline-rich proteins. This study found that, among 306 children between the ages of 5 to 15 years, there is a significant increase in the decayed-missing-filled tooth surface (DMFS) score of the permanent teeth with age in children with the specific proline-rich protein phenotypes Pa and Pr. However, the increase in DMFS score of the permanent teeth of children was significantly greater in children with Pa+ and Pr22 than in those with the other phenotypes (Pa- or Pr11 and Pr12). The previously established close correlation between the Pa and Pr phenotypes and the genetic variants of salivary peroxidase (a powerful antibacterial system in the oral cavity) may provide an explanation for the relationship of certain proline-rich protein phenotypes to dental caries.

Adolescent↗

PubMed1986

Production of an antibody to mouse salivary androgen binding protein (ABP) and its use in identifying a prostate protein produced by a gene distinct from Abp.

We previously demonstrated polymorphism of a mouse salivary protein which, because of its ability to bind androgen, we designated androgen binding protein (ABP) and its structural gene, Androgen binding protein (Abp). This report describes the purification of salivary ABP and presents the amino acid composition of its subunits. Using an antibody raised against the purified protein, we demonstrated the presence of cross-reactive material (CRM) in mouse parotid, submaxillary, sublingual, and prostate glands by double immunodiffusion. Immunohistochemical detection of proteins on electroblots of polyacrylamide electrophoresis and isoelectric focusing gels, however shows that the prostate CRM is a protein with electrophoretic and isoelectric focusing behavior distinct from that of salivary ABP isoproteins. Because the DBA/2J strain has a variant of salivary ABP, that strain was analyzed to determine if a prostate ABP-CRM variant was present. The approach was hampered by an inability to detect CRM in the prostates of DBA/2J mice. Prostate CRM was detected, however, in some progeny from repeated backcrosses of DBA/2J X C3H/St hybrids to the C3H/St and DBA/2J parental strains. The prostate CRM detected in samples from animals heterozygous for salivary Abp appears to be identical to C3H/St prostate CRM, suggesting that the gene controlling prostate ABP-CRM is related to, but distinct from, Abp. The reason for reduced or absent CRM in the prostates of DBA/2J males is unknown but this finding suggests that there are strain-related differences in the expression of this prostate protein.

Amino Acids↗

PubMed1985

Description of a genetic polymorphism of a human proline-rich salivary protein, Pc, and its relationship to other proteins in the salivary protein complex (SPC).

A new polymorphism, Pc, has been identified in human saliva. Two proteins, Pc 1 and Pc 2, are determined by alleles Pc1 and Pc2, respectively, which show autosomal codominant inheritance. No null phenotype has been encountered in 225 randomly collected salivas. The frequencies of the two alleles differ in the Black and White American populations, with Pc1 and Pc2 being 0.670 and 0.330 in the Black (N = 47) and 0.461 and 0.539 in the White (N = 178) populations, respectively. The alleles are in equilibrium in the two populations and segregation analyses (30 families) do not suggest the existence of a null allele in either population. Of seven polymorphic human salivary proteins determined by genes in the salivary protein complex (SPC), Pc phenotypes show association only with Ps phenotypes. Based on that association, our linkage studies, and the biochemical similarities with other SPC proteins, we tentatively conclude that Pc is a member of the SPC, bringing the total number of genes in that group to 13.

Alleles↗

PubMed1985

Characterization of phosphohydrolase activity in bovine spleen extracts: identification of a bis(p-nitrophenyl)phosphate-hydrolyzing activity (phosphodiesterase IV) which also acts on adenosine triphosphate.

Several bovine spleen enzymes with acid pH optima, some of which hydrolyze bis(p-nitrophenyl)phosphate and therefore fit the definition of "phosphodiesterase IV," were partially separated by isoelectric focusing and ion-exchange techniques. The activities were characterized by zymogram analysis with the aid of p-nitrophenyl and 4-methylumbelliferyl phosphate and phosphonate substrates. A number of these enzymes meet the criteria for phosphodiesterase I or other phosphodiesterases. However, the predominant phosphodiesterase I hydrolyzes the bis(p-nitrophenyl)-and 4-methylumbelliferyl phosphates, p-nitrophenyl and 4-methylumbelliferyl phenylphosphonate, and ATP at the beta-gamma bond, but not p-nitrophenyl or 4-methylumbelliferyl 5'-thymidylate (the usual PDE I substrates). These properties, as well as the pH optimum, distinguish the activity from the previously described, alkaline pH optimum PDE I. A second phosphodiesterase hydrolyzes only the phenylphosphonates. Several other activities, less well described, are apparent on zymograms. None of the phosphodiesterases IV was also a phosphodiesterase II (no hydrolysis of 4-methylumbelliferyl 3'-thymidylate).

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1985

Localization of the human salivary protein complex (SPC) to chromosome band 12p13.2.

In situ hybridization of a 3H-labeled probe containing a fragment from PRP-1, a genomic clone with human salivary proline-rich protein gene sequences, revealed significant labeling on the short arm of human chromosome 12 in metaphase preparations from two individuals. Fifty-three percent of metaphases exhibited labeling on one or both chromosomes 12. Additional cells scored at the 850-1,000 band level revealed a significant proportion (52% [32/61] grains, p less than 0.005) of the labeled sites on chromosome 12 to be on band 12p13.2. This probe for a human salivary proline-rich protein gene fragment, probably PMS, is from a cluster of 13 linked genes designated as the human salivary protein complex (SPC). Studies of the DNA of human-mouse somatic-cell hybrids have assigned the SPC to chromosome 12, but have not provided a regional localization (Azen et al, 1985). This paper reports the localization of the SPC to a specific chromosomal band, 12p13.2.

Animals↗

PubMed1985

An amylase-producing serous cystadenocarcinoma of the ovary.

A patient with an amylase-producing serous cystadenocarcinoma of the ovary had elevated serum and urine amylase levels and high levels of amylase in pleural and ascitic fluids. Serum and urine amylase levels reflected both surgical removal of tumor mass and response to chemotherapy. Tumor homogenates had pronounced amylase activity. Salivary type amylase isozyme patterns were found in electrophoresis of samples from all sources. Ascites tumor cells were successfully cultured and salivary type amylase was found in the culture media throughout 5 passages. The tumor was classified by light microscopy as poorly differentiated serous cystadenocarcinoma. Ultrastructural studies on the tumor were consistent with that diagnosis. Amylase was detected in the cells of the tumor examined by the immunoperoxidase technique.

Amylases↗

PubMed1985

The human salivary protein complex (SPC): a large block of related genes.

We have shown that genes for at least six human parotid proteins, parotid acidic protein (Pa), proline-rich protein (Pr), double-banded protein (Db), glycoprotein (Gl), parotid middle-band protein (Pm), and parotid-size variant (Ps) are linked. We have designated this complex of genes as the salivary protein complex (SPC). Several of the genes in this complex show marked associations that are most likely the result of linkage disequilibrium. It seems likely that the SPC arose through the process of gene duplication. This hypothesis is supported by the results of our present study that demonstrate the biochemical similarity of the protein products of several SPC genes. The amino acid compositions of the major SPC proteins are compared, including several (Ps 1 and 2, and Db) that have not been published. All of these proteins are quite similar and consist to a large extent of the amino acids, proline, glycine, and gix (glutamine and/or glutamic acid).

Computers↗

PubMed1984

Multiple gene action determining a mouse salivary protein phenotype: identification of the structural gene for androgen binding protein (Abp).

A novel variation in electrophoretic phenotype is described for a mouse salivary androgen binding protein (Abp). Crosses show that the variation is inherited in an autosomal codominant manner and protein characterization studies show that the variant Abp differs in isoelectric point from the common form of the protein. Those observations suggest that the variation involves the structural gene for the mouse salivary Abp. The genetic studies also show that the electrophoretic mobility of the variant Abp can be influenced by the sex-limited saliva pattern (Ssp) gene. The SspS allele alters the electrophoretic mobility of Abp in males at puberty or in females which have received exogenous testosterone [Karn, R.C., Dlouhy, S.R., Springer, K.R., Hjorth, J.P., and Nielsen, J.T. (1982). Biochem Genet. 20:493]. This study shows that Abp and Ssp are distinct genes which are not closely linked and that SspS is trans active in F1 (Abpa/Abpb, SspS/SspF) males.

Alleles↗