Recognize rat C-peptide I and rat proinsulin; low affinity to rat and mouse C-peptides II. Not react with mouse C-peptide I. Best pairs for rat C-peptide I immunodetection (coating - conjugate): CC34 - CI-0. Can be used for separate or consistent detection of rat C-peptide isoforms (rat C-peptide I and/or rat C-peptide II) in biological samples.