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Biomedical subjects

A Swaroop

Publications and source records attributed to A Swaroop.

At least 73 records · Page 4Linked to original sources
PubMed1993

Molecular characterization of the murine neural retina leucine zipper gene, Nrl.

The NRL gene (D14S46E) is expressed in cells of human retina and encodes a putative DNA-binding protein of the leucine zipper family. Here we describe the analysis of the murine homolog of the NRL gene, Nrl. Various cDNAs resulting from alternate polyadenylation are characterized. The deduced polypeptide sequence is highly conserved between mouse and human, with an identical basic motif and leucine zipper domain. The nucleotide sequences in the 5' and 3'-untranslated regions also show significant homology. The 3'-untranslated region contains a polymorphic AGG-trinucleotide repeat. The murine Nrl gene consists of three exons; of these, the first is untranslated. The 5'-upstream promoter region has no canonical TATA box, but contains consensus binding site sequences for several DNA-binding proteins. Analysis of RNA from adult mouse tissues confirms the retina-specific expression of Nrl. This study provides the basis for dissecting the cis-regulatory elements involved in the retina-specific expression and for the development of an experimental model to investigate the function or any diseases associated with this gene in humans.

Amino Acid Sequence↗
PubMed1993

cDNA libraries from human tissues and cell lines.

We report the construction of 34 cDNA libraries from human tissues and cell lines in lambda phage vectors (Charon BS, lambda gt11, lambda SHK, or lambda zapII). The cDNA was synthesized from poly A+ RNA, using oligo-dT as a primer, and size-selected before ligation to vector arms. High-complexity cDNA libraries from human tissues and cell lines should be a valuable resource for genome mapping studies and identification of disease genes.

Bacteriophage lambda↗
PubMed1993

Study of serum amylase in acute viral hepatitis.

Serum total Amylase and its heat stable fraction (HSF) were studied in 10 healthy controls, and 20 patients of Viral hepatitis. A highly significant (p < 0.001) elevation in the levels of total and HSF of Serum amylase was found in acute viral hepatitis, mainly due to the HSF which originates from hepatitis. The levels declined significantly after 10 days when the disease regressed and there was evidence of improvement in clinical and functional status of the liver. Hence an estimation of total and HSF of Serum amylase proved to have some diagnostic and prognostic importance.

Acute Disease↗
PubMed1992

A conserved retina-specific gene encodes a basic motif/leucine zipper domain.

Using subtraction cloning, we have isolated a human cDNA, AS321, which is expressed in retina and retinoblastoma cell lines but not in any other tissue or cell line tested. AS321 mRNA is detected in all cells of neural retina, with a high level of expression in photoreceptors. The polypeptide sequence deduced from the cDNA reveals consensus phosphorylation sites for protein kinase A and proline-directed protein kinase. Its C-terminal region contains a basic motif and a leucine zipper domain similar to the DNA binding proteins of the jun and fos oncoprotein family, and it shows a strong similarity to the product of an avian retroviral oncogene, v-maf. The gene for AS321 is conserved during evolution and is expressed in vertebrate retina. We propose to name the gene NRL (neural retina leucine zipper.

Amino Acid Sequence↗
PubMed1992

Expressed sequence tags and chromosomal localization of cDNA clones from a subtracted retinal pigment epithelium library.

Expressed sequence tags (ESTs) provide useful molecular landmarks for physical mapping and identify the position of an expressed region in the genome. The use of subtracted cDNA libraries enriched for tissue-specific genes as a source of ESTs should reduce the repetitive isolation of constitutively expressed sequences. We report here the sequence tags from the 3'-end region of 58 new directionally cloned cDNAs from a subtracted human retinal pigment epithelium (RPE) cell line library. Eight of the cDNAs have been assigned to human chromosomes using PCR-based EST assays. Chromosomal mapping of subtracted RPE cDNA clones may also help in identifying candidate genes for inherited eye diseases.

Base Sequence↗
PubMed1992

Neural retina-specific leucine zipper gene NRL (D14S46E) maps to human chromosome 14q11.1-q11.2.

The product of a neural retina-specific gene, NRL, belongs to the "leucine zipper" family of DNA-binding proteins and has a strong similarity to the v-maf oncogene product. The NRL gene maps to human chromosome 14 by Southern blot analysis of genomic DNA from a human-rodent somatic cell hybrid panel. In situ hybridization to metaphase chromosomes has further sublocalized the gene to the region 14q11.1-q11.2. D14S46E has now been assigned to the NRL gene. Because of its specific pattern of expression, NRL is a candidate gene for retinal diseases.

Animals↗
PubMed1991

Differential expression of novel Gs alpha signal transduction protein cDNA species.

The Gs alpha guanine nucleotide-binding signal transduction protein is part of a heterotrimeric complex that is involved in the stimulation of adenylate cyclase upon activation of membrane receptors. We report the characterization of 16 Gs alpha cDNA clones isolated from the human adult retina and fetal eye libraries. Molecular heterogeneity in the 5'-region defines four novel Gs alpha cDNA species which are generated either by alternate splicing or by using alternative promoter. The novel exons upstream of exon 2 interrupt the highly conserved 'region A' in the Gs alpha polypeptide. Non-AUG codons in the novel 5'-exon can initiate translation of these Gs alpha species in vitro. Reverse transcription of total RNA coupled with polymerase chain reaction (RTPCR) using specific primers and in situ hybridization to mRNA in baboon tissue sections with a specific oligonucleotide probe show a high level of expression of these species in retina and brain but not in liver. Differential expression of alternatively spliced Gs alpha species suggests novel signal transducing pathways.

Aged↗
PubMed1991

Sequence analysis, expression and chromosomal localization of a gene, isolated from a subtracted human retina cDNA library, that encodes an insulin-like growth factor binding protein (IGFBP2).

The metabolic functions of insulin-like growth factors (IGFs) I and II are modulated by a family of binding proteins which are present in biological fluids and are synthesized by a variety of cell types. A cDNA clone, isolated at random from a subtracted human retina library, has been identified to code for a novel IGF-binding protein (IGFBP2) by its sequence homology to the peptide sequence of IGF binding proteins purified from bovine MDBK and rat BRL-3A cells. The complete nucleotide sequence of the IGFBP2 cDNA is 1406 bp long, contains 66% G-Cs and an open reading frame of 328 amino acids with a putative signal or pro-peptide of 39 residues. The mature polypeptide of 289 amino acids has 18 cysteines, a putative ATP-binding site and an RGD tripeptide. The 1.4 kb IGFBP2 transcript is expressed in several human tissues including fetal eye and fetal brain, but not in the human lymphoblastoid cell line against which the retinal cDNA library was subtracted. In situ hybridization to sections of mouse retina localized the mRNA for IGFBP2 primarily in the outer nuclear layer of photoreceptors. Southern blot analysis of DNA from human x rodent and mouse x rodent somatic cell hybrids assigned the gene for IGFBP2 to human chromosome 2q33-qter and mouse chromosome 1 in a known conserved syntenic region.

Aged↗
PubMed1990

Origin of mutations in two families with X-linked chronic granulomatous disease.

The most common X-linked recessive form of chronic granulomatous disease (X-CGD) is characterized by the absence of cytochrome b558 in neutrophils. In a rare variant form of X-CGD, cytochrome b558 is present but not functional. The gene (locus symbol CYBB) was localized to band Xp21 by studies of patients with small chromosome deletions. The gene was cloned based on its location and found to encode the 91-Kd subunit of the cytochrome b558 complex. Most female carriers for X-CGD can be identified by their X-inactivation mosaicism; on average 50% of their neutrophils express the mutant phenotype and fail to reduce nitroblue tetrazolium (NBT). In 2 of 4 families studied, the maternal grandmothers had normal NBT tests, suggesting either nonrandom X-inactivation or new mutations. Restriction fragment length polymorphism analysis using closely linked flanking markers or the NsiI polymorphism detected by the CYBB probe itself, allowed us to identify the X chromosome carrying the mutation as derived from a healthy NBT-positive maternal grandfather. The mothers of the affected boys must have received a paternal X chromosome carrying a new mutation, consistent with the maternal grandmothers' normal NBT tests. In all of eight potential carriers studied, the results of the NBT and DNA marker testing were in complete agreement. Prenatal diagnosis by DNA testing can be performed in early gestation obviating the need for fetal blood sampling.

DNA↗
PubMed1990

Chromosomal localization and cDNA sequence of human ralB, a GTP binding protein.

The human ra1 proteins share more than 50% homology and some properties with the ras proteins. The RALB gene, a new member of the ra1 family, has been isolated, sequenced, and assigned to human chromosome 2 cen-q13. One other member of this family, RALA, has been previously mapped to the short arm of human chromosome 7.

Amino Acid Sequence↗
PubMed1988

Molecular analysis of the cDNA for human SPARC/osteonectin/BM-40: sequence, expression, and localization of the gene to chromosome 5q31-q33.

Human cDNA clones encoding the extracellular calcium-binding, acidic glycoprotein known as SPARC, osteonectin, or BM-40 were isolated from a placental cDNA library. Two polyadenylated transcripts of 2.2 and 3.0 kb were detected in human tissues and cultured cells by Northern blot analysis, and cDNAs for both transcripts were characterized. The 2133-bp sequence of the more abundant (major) transcript contains an open reading frame for 303 amino acids. The deduced polypeptide has extensive amino acid sequence identity with mouse SPARC. The larger and minor 3.0-kb cDNA has an identical coding region but utilizes a downstream polyadenylation signal. Gene localization studies have revealed a single chromosomal site at 5q31-q33 by somatic cell hybrid analysis and in situ chromosomal hybridization. Furthermore, pulsed-field gel electrophoresis of human genomic DNA cleaved with different rare-cutting restriction enzymes and hybridized with SPARC cDNA probes revealed single or double fragments of less than 50 to about 150 kb. The evidence is consistent with a single locus for SPARC in humans. The gene was found to be differentially expressed in many human tissues and in an osteogenic sarcoma, but not in other transformed cells.

Amino Acid Sequence↗