Two splicing variants of a new inhibitor of apoptosis gene with different biological properties and tissue distribution pattern

Yaqoub Ashhab, Akram Alian, Aaron Polliack, Amos Panet, Dina Ben Yehuda*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

191 Scopus citations


Using homology searches, we identified a novel human inhibitor of apoptosis (IAP) gene. This gene has two splicing variants that contain open reading frames of 298 and 280 amino acids and both contained a single copy of baculovirus IAP repeat (BIR) and RING domain. We refer here to the longer and shorter variants as Livin α and β, respectively. Semiquantitative reverse transcriptase-polymerase chain reaction demonstrated a tissue-specific and non-correlated expression pattern in both adult and fetal tissues. Both mRNA variants were detected in various transformed cell lines. Despite their very close similarity, the two isoforms have different antiapoptotic properties. Both isoforms have a significant antiapoptotic activity in the Jurkat T cell line after triggering apoptosis via tumor necrosis factor and CD95 receptors. The Livin α but not β protects cells from apoptosis induced by staurosporine, but in contrast, apoptosis initiated by etoposide was blocked only by the β isoform. This difference in biological activities may indicate the presence of critical amino acids outside the BIR and RING domains. These functional and tissue distribution differences of Livin α and β suggest that Livin may play a complex role in the regulation of apoptosis.

Original languageAmerican English
Pages (from-to)56-60
Number of pages5
JournalFEBS Letters
Issue number1-2
StatePublished - 20 Apr 2001
Externally publishedYes

Bibliographical note

Funding Information:
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Funding Information:
This research was supported by the NASA Exobiology Program and the Goddard Center for Astrobiology. Astrophysics at QUB is supported by a grant from STFC.


  • Alternative splicing
  • Antiapoptotic gene
  • Inhibitor of apoptosis


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