PubMed Health⌕ Search

Biomedical subjects

J G Izant

Publications and source records attributed to J G Izant.

5 recordsLinked to original sources
PubMed1991

Xenopus annexin II (calpactin I) heavy chain has a distinct amino terminus.

We have isolated cDNAs encoding annexin II (calpactin I) heavy chain homologues from a Xenopus oocyte cDNA library. Two of the clones are full length, while two appear to be derived from incompletely spliced mRNAs. The 1230- and 1240-base pair full length clones are 99% identical, and both have 84 bases of 5'-untranslated sequence, 1020-base open reading frames, and either 126- or 136-base 3'-untranslated domains. Northern blots show a 1.4-kilobase (kb) annexin II heavy chain transcript throughout oogenesis and in mature eggs. Xenopus annexin II mRNA levels are constant during early embryogenesis, but decrease at 8 h. After midblastula transition, the steady state level of the 1.4-kb transcript increases substantially, and a 3.3-kb transcript appears. Adult brain, heart, striated muscle, and liver contain moderate amounts of the 1.4-kb transcript, while skin has the 3.3-kb transcript and very high levels of the 1.4-kb transcript. Synthetic mRNA derived from the Xenopus annexin II cDNAs directs the synthesis of an apparent Mr = 36,500 polypeptide when microinjected into Xenopus oocytes. The predicted 339-amino acid protein products are 80% identical with murine annexin II heavy chain. Most of the differences are concentrated in the amino end from residues 15 to 24. The Xenopus annexin II heavy chain lacks the highly conserved tyrosine at position 23 which is the site of src oncogene tyrosine kinase phosphorylation in the murine protein. These results demonstrate that Xenopus oocytes contain an annexin II (calpactin I) heavy chain mRNA with a distinct amino terminus and suggest that multiple annexin II isoforms may be expressed during amphibian embryogenesis and development.

Amino Acid Sequence↗
PubMed1985

Constitutive and conditional suppression of exogenous and endogenous genes by anti-sense RNA.

Plasmid DNA directing transcription of the noncoding (anti-sense) DNA strand can specifically inhibit the expression of several test genes as well as normal, endogenous genes. The anti-sense plasmid constructions can be introduced into eukaryotic cells by transfection or microinjection and function in both transient and stable transformation assays. Anti-sense transcripts complementary to as little as 52 bases of 5' untranslated target gene mRNA specifically suppress gene activity as well as, or more efficiently than, anti-sense transcripts directed against the protein coding domain alone. Conditional anti-sense inhibition is accomplished with the use of hormone-inducible promoter sequences. Suppression of endogenous actin gene activity by anti-sense RNA is detected as a decrease in growth rate and as a reduction in the number of actin microfilament cables. These observations suggest that anti-sense RNA may be generally useful for suppressing the expression of specific genes in vivo and may be a potential molecular alternative to classical genetic analysis.

Acetyltransferases↗
PubMed1977

Invariance and heterogeneity in the major structural and regulatory proteins of chick muscle cells revealed by two-dimensional gel electrophoresis.

A two-dimensional gel electrophoresis system is used to investigate some of the properties of desmin, the major subunit of the 100-A filaments from chick muscle cells, and to compare these properties to those of the other major contractile and regulatory proteins of muscle. Desmin from embryonic and adult smooth, skeletal, and cardiac muscle cells is resolved into two isoelectric variants, alpha and beta, which possess slightly different electrophoretic mobilities in sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Both the alpha and the beta variants from all six preparations appear to be identical in isoelectric point and apparent molecular weight. The alpha and beta desmin are present in approximately equal amounts in all three types of muscle, suggesting that both isoelectric variants of desmin serve as the structural subunits of the 100-A filaments in chick muscle cells. Tropomyosin also can be resolved into two subunits, alpha and beta, in all three types of muscle. However, in each type of muscle both subunits differ from their counterparts in the other types of muscle, either by molecular weight or by isoelectric point. These results indicate that, with regard to apparent isoelectric point and molecular weight, desmin, a major muscle structural protein, is invariant, while tropomyosin, a major muscle regulatory protein, exhibits heterogeneity in the three types of muscle.

Actins↗