New mechanisms of hormone secretion: MDR-like gene products as extrusion pumps for hormones?

K. F. Becker, H. Allmeier, V. Hollt

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


P-glycoprotein, the product of the multidrug resistance (MDR1) gene, is an ATP-driven transmembrane pump that increases the resistance of cells by actively exporting toxic chemicals. In addition to transporting anticancer drugs, P-glycoprotein has been reported to extrude a variety of lipophilic drugs, such as calcium channel blockers, phenothiazines, cyclosporines etc. Interestingly, recent experiments suggest that steroid hormones may be physiologic substrates for P-glycoprotein. In addition, there exists a family of transporter genes with high structural homology to P-glycoprotein, the so-called ABC (ATP-binding casette) family. Although the physiological ligands for most of these transporters are unknown, there is increasing evidence that peptides may be transported by some of these proteins. Thus, the α-factor, a farnesylated pheromone with 13 amino acids, is exported from yeast cells by the product of the STE6 gene, a transporter protein with high homology to P-glycoprotein. Recently, we have cloned a novel member of the ABC-transporter gene family from neuroblastoma x glioma hybrid (NG-108-15) cells. This putative transporter gene ('NG-TRA')) is expressed in the adrenal gland, kidney and in the brain. High amounts of NG-TRA mRNA are found in a variety of human brain tumors. Whether NG-TRA and/or other MDR-related transporters are involved in the transport of steroids, peptide hormones or growth factors remains to be established. If so, the cellular export of hormones by active pumps may represent a new mechanism of hormone secretion.

Original languageEnglish
Pages (from-to)210-213
Number of pages4
JournalHormone and Metabolic Research
Issue number5
StatePublished - 1992
Externally publishedYes


  • ABC-transporter
  • MDR
  • NG-TRA
  • STE6 a-factor
  • growth factors
  • steroid hormones


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