Latherin: A surfactant protein of horse sweat and saliva

Rhona E. McDonald, Rachel I. Fleming, John G. Beeley, Douglas Bovell, Jian R. Lu, Xiubo Zhao, Alan Cooper, Malcolm W. Kennedy

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

Horses are unusual in producing protein-rich sweat for thermoregulation, a major component of which is latherin, a highly surface-active, non-glycosylated protein. The amino acid sequence of latherin, determined from cDNA analysis, is highly conserved across four geographically dispersed equid species (horse, zebra, onager, ass), and is similar to a family of proteins only found previously in the oral cavity and associated tissues of mammals. Latherin produces a significant reduction in water surface tension at low concentrations (≤1 mg ml-1), and therefore probably acts as a wetting agent to facilitate evaporative cooling through a waterproofed pelt. Neutron reflection experiments indicate that this detergent-like activity is associated with the formation of a dense protein layer, about 10 Å thick, at the air-water interface. However, biophysical characterization (circular dichroism, differential scanning calorimetry) in solution shows that latherin behaves like a typical globular protein, although with unusual intrinsic fluorescence characteristics, suggesting that significant conformational change or unfolding of the protein is required for assembly of the air-water interfacial layer. RT-PCR screening revealed latherin transcripts in horse skin and salivary gland but in no other tissues. Recombinant latherin produced in bacteria was also found to be the target of IgE antibody from horse-allergic subjects. Equids therefore may have adapted an oral/salivary mucosal protein for two purposes peculiar to their lifestyle, namely their need for rapid and efficient heat dissipation and their specialisation for masticating and processing large quantities of dry food material.

Original languageEnglish
Article numbere5726
JournalPLoS One
Volume4
Issue number5
DOIs
Publication statusPublished - 29 May 2009
Externally publishedYes

Fingerprint

sweat
Sweat
saliva
Saliva
Surface-Active Agents
surfactants
Horses
horses
Proteins
proteins
Equidae
Water
mouth
Wetting Agents
Air
skin glands
furs and pelts
Salivary Proteins and Peptides
circular dichroism spectroscopy
Neutron reflection

ASJC Scopus subject areas

  • Medicine(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

McDonald, R. E., Fleming, R. I., Beeley, J. G., Bovell, D., Lu, J. R., Zhao, X., ... Kennedy, M. W. (2009). Latherin: A surfactant protein of horse sweat and saliva. PLoS One, 4(5), [e5726]. https://doi.org/10.1371/journal.pone.0005726

Latherin : A surfactant protein of horse sweat and saliva. / McDonald, Rhona E.; Fleming, Rachel I.; Beeley, John G.; Bovell, Douglas; Lu, Jian R.; Zhao, Xiubo; Cooper, Alan; Kennedy, Malcolm W.

In: PLoS One, Vol. 4, No. 5, e5726, 29.05.2009.

Research output: Contribution to journalArticle

McDonald, RE, Fleming, RI, Beeley, JG, Bovell, D, Lu, JR, Zhao, X, Cooper, A & Kennedy, MW 2009, 'Latherin: A surfactant protein of horse sweat and saliva', PLoS One, vol. 4, no. 5, e5726. https://doi.org/10.1371/journal.pone.0005726
McDonald RE, Fleming RI, Beeley JG, Bovell D, Lu JR, Zhao X et al. Latherin: A surfactant protein of horse sweat and saliva. PLoS One. 2009 May 29;4(5). e5726. https://doi.org/10.1371/journal.pone.0005726
McDonald, Rhona E. ; Fleming, Rachel I. ; Beeley, John G. ; Bovell, Douglas ; Lu, Jian R. ; Zhao, Xiubo ; Cooper, Alan ; Kennedy, Malcolm W. / Latherin : A surfactant protein of horse sweat and saliva. In: PLoS One. 2009 ; Vol. 4, No. 5.
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