Isolation of a cDNA clone for beta 1-4 galactosyltransferase from embryonic chicken brain and comparison to its mammalian homologs.

Based on the observed biochemical and immunological similarities between bovine beta 1-4 galactosyltransferase (GalT) and a developmentally regulated galactosyltransferase (GalT-4; UDP-Gal:Lc3 beta 1-4 GalT) from embryonic chicken brain, a genetic similarity between the two enzymes has been postulated. To test our hypothesis, we have employed a reverse transcription-polymerase chain reaction (RT-PCR)based approach and isolated a approximately 600 bp cDNA clone from embryonic chicken brain mRNA. Our results indicate that, within the approximately 600 bp fragment, the avian cDNA nucleotide sequence is 74% homologous to the human beta 1-4 galactosyltransferase cDNA. Similarity and identity between the predicted amino acid sequences of the two galactosyltransferases are 75% and 61%, respectively. Similar to its mammalian counterparts, the embryonic chicken brain galactosyltransferase gene appears to encode multiple mRNA transcripts (2.3 and 1.4 kb) and shows multiple bands on a Southern blot (18.6, 12.9, 10.5 and 3.7 kb) indicating that the avian gene is either polyexonic and/or it belongs to a multiple gene family.