Occurrence of a multimeric high-molecular-weight glyceraldehyde-3-phosphate dehydrogenase in human serum

Rani Kunjithapatham, Jean Francois Geschwind, Lauren Devine, Tatiana N. Boronina, Robert N. Omeally, Robert N. Cole, Michael S. Torbenson, Shanmugasundaram Ganapathy-Kanniappan

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Cellular glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a phylogenetically conserved, ubiquitous enzyme that plays an indispensable role in energy metabolism. Although a wealth of information is available on cellular GAPDH, there is a clear paucity of data on its extracellular counterpart (i.e., the secreted or extracellular GAPDH). Here, we show that the extracellular GAPDH in human serum is a multimeric, high-molecular-weight, yet glycolytically active enzyme. The high-molecular-weight multimers of serum GAPDH were identified by immunodetection on one- and two-dimensional gel electrophoresis using multiple antibodies specific for various epitopes of GAPDH. Partial purification of serum GAPDH by DEAE Affigel affinity/ion exchange chromatography further established the multimeric composition of serum GAPDH. In vitro data demonstrated that human cell lines secrete a multimeric, high-molecular-weight enzyme similar to that of serum GAPDH. Furthermore, LC-MS/MS analysis of extracellular GAPDH from human cell lines confirmed the presence of unique peptides of GAPDH in the high-molecular-weight subunits. Furthermore, data from pulse-chase experiments established the presence of high-molecular-weight subunits in the secreted, extracellular GAPDH. Taken together, our findings demonstrate the presence of a high-molecular-weight, enzymatically active secretory GAPDH in human serum that may have a hitherto unknown function in humans.

Original languageEnglish (US)
Pages (from-to)1645-1656
Number of pages12
JournalJournal of Proteome Research
Issue number4
StatePublished - Apr 3 2015


  • 2D gel electrophoresis
  • DEAE Affigel Blue column chromatography
  • extracellular GAPDH
  • multimer
  • serum GAPDH

ASJC Scopus subject areas

  • Biochemistry
  • General Chemistry


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