Molecular cloning of testican-2: defining a novel calcium-binding proteoglycan family expressed in brain

J Neurochem. 1999 Jul;73(1):12-20. doi: 10.1046/j.1471-4159.1999.0730012.x.


We have screened a human cDNA library using an expressed sequence tag related to the BM-40/secreted protein, acidic and rich in cysteine (SPARC)/osteonectin family of proteins and isolated a novel cDNA. It encodes a protein precursor of 424 amino acids that consists of a signal peptide, a follistatin-like domain, a Ca2+-binding domain, a thyroglobulin-like domain, and a C-terminal region with two putative glycosaminoglycan attachment sites. The protein is homologous to testican-1 and was termed testican-2. Testican-1 is a proteoglycan originally isolated from human seminal plasma that is also expressed in brain. Northern blot hybridization of testican-2 showed a 6.1-kb mRNA expressed mainly in CNS but also found in lung and testis. A widespread expression in multiple neuronal cell types in olfactory bulb, cerebral cortex, thalamus, hippocampus, cerebellum, and medulla was detected by in situ hybridization. A recombinant fragment consisting of the Ca2+-binding EF-hand domain and the thyroglobulin-like domain of testican-2 showed a reversible Ca2+-dependent conformational change in circular dichroism studies. Testican-1 and -2 form a novel Ca2+-binding proteoglycan family built of modular domains with the potential to participate in diverse steps of neurogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Brain Chemistry*
  • Calcium / metabolism*
  • Cloning, Molecular*
  • DNA, Complementary / chemistry
  • DNA, Complementary / isolation & purification
  • Fetus
  • Humans
  • In Situ Hybridization
  • Lung / chemistry
  • Male
  • Mice
  • Molecular Sequence Data
  • Proteoglycans / chemistry
  • Proteoglycans / genetics*
  • Proteoglycans / metabolism
  • RNA, Messenger / analysis
  • Testicular Hormones / genetics
  • Testis / chemistry
  • Tissue Distribution


  • DNA, Complementary
  • Proteoglycans
  • RNA, Messenger
  • SPOCK1 protein, human
  • SPOCK2 protein, human
  • Spock1 protein, mouse
  • Spock2 protein, mouse
  • Testicular Hormones
  • Calcium