Department of Molecular and Medical Pharmacology, UCLA School of Medicine 90095, USA.
We present the nucleotide and deduced amino acid sequence of a human systeine string protein (csp) and a unique truncated csp variant that derives from the retention of an exonic sequence that introduces a premature, in-frame stop codon. Low stringency Southern analysis is compatible with the presence of a single human csp gene. Northern analysis reveals that human csp mRNA has both a more heterogeneous size distribution and a more widespread tissue distribution than previously reported for other csps. Exemplifying this is the fact that csp immunoreactivity is detected in Triton X-114 extracts of human blood, an observation which may facilitate blood-based diagnostic assays of csp status in man.