A retinoic acid-inducible mRNA from human erythroleukemia cells encodes a novel tissue transglutaminase homologue.
A 1.9-kilobase (kb) cDNA for a new transglutaminase protein has been cloned and sequenced from retinoic acid-induced human erythroleukemia (HEL) cells. Full-length cDNA analysis reveals an open reading frame coding for a polypeptide of 548 amino acid residues with a molecular weight of 61,740. The deduced amino acid sequence exhibited 98% identity to the human cellular transglutaminase sequence. The cysteine at position 277 in the active site and the putative Ca(2+)-binding pocket at residues 446-453 of cellular transglutaminase are conserved. Such evidence predicts that the encoded protein product is likely to be a transglutaminase homologue (TGase-H). Immunoprecipitation of the in vitro translation products from a synthetic TGase-H mRNA and from total protein of cultured erythroleukemia HEL cells revealed a protein with a molecular weight of 63,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Northern blot analysis of HEL cells and normal human fibroblast cells WI-38 using a cellular TGase probe detected the 1.9- and 4.0-kb RNA species at a relative abundance of 1:3 and 1:7, respectively. The 3'-end of the human cellular transglutaminase mRNA was also cloned and sequenced to allow comparison to the 3'-end of TGase-H reported here. This new piece gives a full length of 4012 nucleotides (4.0 kb) for human cellular transglutaminase. Comparison of the 5'-end (bases 1-1747) of the 1.9- and 4.0-kb cDNA sequences revealed a very high degree of identity. Beginning with base 1748, the sequences diverge showing no homology. The divergence point correlates with known intron-exon consensus boundaries indicative of alternative splicing.
Samuel Roberts Noble Foundation, Inc., Biomedical Division/Nutrition Section, Ardmore, Oklahoma 73402.
B M
BM
Fraij
P J
PJ
Birckbichler
M K
MK
Patterson
K N
KN
Lee
R A
RA
Gonzales
D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D004915:Leukemia, Erythroblastic, Acute / Q000201:enzymology*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D015183:Restriction Mapping; D016415:Sequence Alignment; D011503:Transglutaminases / Q000737:chemistry / Q000235:genetics*; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D014212:Tretinoin; D004247:DNA; D011503:Transglutaminases