title: Klotho is a serum factor related to human aging.
abstract: BACKGROUND
  Does klotho (KL) protein exist in human serum, and is there any correlation between KL protein in serum with human aging? In order to answer those questions, we identified KL protein in human serum and established the correlation between KL protein in human serum and aging.
  
  
  METHODS
  We prepared a polyclonal antibody against human KL protein that was able to recognize the C-terminal of human secreted KL protein. Western blot and enzyme-linked immunosorbent assay (ELISA) were used to identify KL protein in human serum.
  
  
  RESULTS
  In Western blot, the antibody specifically recognized a 60-kD KL protein in both human and mice serum. The population aged from 0 to 91 years screened by ELISA revealed that the level of serum KL declined while age increased, though each individual level was variable and that the trend of decreasing in serum KL had no difference in sex.
  
  
  CONCLUSIONS
  Our data suggest that KL is a serum factor related to human aging.
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Life Science, Peking University, Beijing 100871, China.
authors.forename: Neng-ming
authors.initials: NM
authors.lastname: Xiao
authors.forename: Yan-ming
authors.initials: YM
authors.lastname: Zhang
authors.forename: Quan
authors.initials: Q
authors.lastname: Zheng
authors.forename: Jun
authors.initials: J
authors.lastname: Gu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D003001:Cloning, Molecular; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005966:Glucuronidase; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D000090265:Klotho Proteins; D008297:Male; D008565:Membrane Proteins / Q000097:blood*; D008875:Middle Aged
chemical_list: D008565:Membrane Proteins; D005966:Glucuronidase; D000090265:Klotho Proteins