The status and expression of Rb gene was detected and analyzed in 19 surgical retinoblastoma specimens using Rb cDNA 3. 8 kb and 0. 9 kb fragment as probe and antibodies specific for synthetic Rb peptide or expressive...The status and expression of Rb gene was detected and analyzed in 19 surgical retinoblastoma specimens using Rb cDNA 3. 8 kb and 0. 9 kb fragment as probe and antibodies specific for synthetic Rb peptide or expressive product of Rb gene expression plasmld. DNA from those tumors had the hemlzygous deletion in 3 cases, the homozygous internal deletion In 2 cases and alterated restriction fragment involving In one copy of Rb gene In 1 case. The quantity of Rb protein demonstrated either absence of reduction in all the 16 cases examined In comparison with that in normal adult retina. It suggested that there were structural or/ and functional defects of Rb gene In retinoblastoma cells and provided evidence to support Knudson' s two hit hypothesis.展开更多
Proinsulin, the precursor of insulin, possesses very low, if any, biological activity. Only after the action of proteolytic enzymes in the β-cells of the pancreas is insulin released from proinsulin with the simultan...Proinsulin, the precursor of insulin, possesses very low, if any, biological activity. Only after the action of proteolytic enzymes in the β-cells of the pancreas is insulin released from proinsulin with the simultaneous release of C-peptide and 2 pairs of basic amino acids. The C-peptide portion of human proinsulin comprises 31 amino acid residues, while this portion from different species exhibits rather big differences in amino acid composition. Although the biological function of C-peptide is not known, the plas-展开更多
文摘The status and expression of Rb gene was detected and analyzed in 19 surgical retinoblastoma specimens using Rb cDNA 3. 8 kb and 0. 9 kb fragment as probe and antibodies specific for synthetic Rb peptide or expressive product of Rb gene expression plasmld. DNA from those tumors had the hemlzygous deletion in 3 cases, the homozygous internal deletion In 2 cases and alterated restriction fragment involving In one copy of Rb gene In 1 case. The quantity of Rb protein demonstrated either absence of reduction in all the 16 cases examined In comparison with that in normal adult retina. It suggested that there were structural or/ and functional defects of Rb gene In retinoblastoma cells and provided evidence to support Knudson' s two hit hypothesis.
文摘Proinsulin, the precursor of insulin, possesses very low, if any, biological activity. Only after the action of proteolytic enzymes in the β-cells of the pancreas is insulin released from proinsulin with the simultaneous release of C-peptide and 2 pairs of basic amino acids. The C-peptide portion of human proinsulin comprises 31 amino acid residues, while this portion from different species exhibits rather big differences in amino acid composition. Although the biological function of C-peptide is not known, the plas-
