Xenopus brevican is expressed in the notochord and the brain during early embryogenesis

A complete cDNA encoding the Xenopus laevis homologue of the aggrecan/versican family member, brevican (Xbcan) was cloned from an embryonic stage 42 cDNA library. In the deduced amino acid sequence, 1152 in length, similarity to the hyaluronan-binding (link) domains of brevicans from other species were present in the N-terminal region as well as EGF-, lectin- and complement regulatory protein-like domains in the C-terminal part, the latter three being characteristic for brevican found within the extracellular matrix (J. Biol. Chem. 269 (1994) 10119). Indeed, Xbcan was secreted into the extracellular space as a soluble protein when expressed in oocytes. No cDNAs encoding a GPI-anchored bcan variant could be isolated from that cDNA library. During embryonic development, the expression of this gene was first observed in the notochord of neurula stage embryos. In addition to this, in tailbuds, Xbcan was also found to be expressed within the fifth and sixth rhombomere of the hindbrain. In tadpole stage embryos, expression was furthermore observed in periventricular regions of the developing brain and the rostral part of the spinal cord.