A Xenopus cysteine string protein with a cysteine residue in the J domain

A cDNA clone encoding a Xenopus cysteine string protein (Xcsp) was isolated and sequenced. The deduced primary sequence of Xcsp is very similar to other vertebrate csps with the exception of a cysteine residue that lies outside of the cysteine-string domain. This cysteine residue replaces a serine that is highly conserved among vertebrate csps, and thus may be of functional importance. Xcsp mRNA appears as a 4.6 kb species on Northern analysis, and immunoblot of Xenopus brain membranes reveals a single, 35 kDa Xcsp that can be deacylated, like other csps.