Human GM3 synthase: a new mRNA variant encodes an NH2-terminal extended form of the protein
| Autor: | Bruno Berra, E. Sottocornola, Simona Milani, Stefania Zava, Irma Colombo, Patrizia Berselli |
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| Jazyk: | angličtina |
| Rok vydání: | 2006 |
| Předmět: |
Gene isoform
DNA Complementary Placenta Molecular Sequence Data Biophysics Codon Initiator HL-60 Cells Biology Biochemistry Substrate Specificity Lactosylceramide Start codon Structural Biology Transcription (biology) Settore BIO/10 - Biochimica Genetics Humans Amino Acid Sequence RNA Messenger music Gene chemistry.chemical_classification Messenger RNA music.instrument Base Sequence Cell Differentiation Molecular biology Sialyltransferases In vitro Amino acid Isoenzymes carbohydrates (lipids) chemistry lipids (amino acids peptides and proteins) GM3 GM3 synthase HL60 cell differentiation Human placenta In vitro translation Transcription |
| Popis: | All human GM3 synthase mRNA variants until now identified predict a protein of 362 amino acids having substrate activity highly restricted to lactosylceramide. In this report we describe the identification of a new GM3 synthase transcript containing an additional translation start codon, located upstream and in-frame with that up to now considered unique translation initiation site in the human GM3 synthase gene. In vitro expression studies showed that the new transcript produces a longer form of human GM3 synthase, that is efficiently translocated into the microsomal lumen and glycosylated. Moreover, stable cDNA transfection into mammalian cells gives rise to a threefold increase of GM3 synthase activity, associated to a broader substrate specificity. Although this transcript has been initially identified in the human placenta, RT-PCR analyses verified the expression of an identical mRNA also in undifferentiated HL60 cells, but not in the monocytic lineage. Altogether, these results are the first demonstration of the existence of a new isoform of human GM3 synthase, which could play an important role during HL60 cell differentiation. The functional relevance of the existence of two isoforms of GM3 synthase is also discussed. |
| Databáze: | OpenAIRE |
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