Proteins of rat serum urine and cerebrospinal fluid: VI. Further protein identifications and interstrain comparison

We have investigated the biological fluids - serum, cerebrospinal fluid, an d urine - of three strains of rats; the present data extend our database (a lso available on-line) and may be of interest for pharmacological and toxic ological investigation. Specifically, we have defined reference maps of the major protein components in cerebrospinal fluid and urine. Compartment-spe cific isoforms were recognized for transferrin and transthyretin. Mass spec trometric data established the cleavage site of the signal peptide and iden tified the N-terminal blocking group of prostaglandin D synthase from rat c erebrospinal fluid. A previously undescribed member of the family of low mo lecular mass rat urinary proteins was characterized as containing a sequenc e similar, but not identical, to the N-terminal region of rat urinary prote in-2 (RUP-2), and divergent from RUP-1.