The use of recombinant human growth hormone for radioiodination and standard preparation in radioimmunoassay.

Recombinant human growth hormone (rec-hGH) obtained by cloning hGH precursor gene, bacterial expression and periplasmic secretion of the authentic, mature form of the hormone was used, after purification and characterization, for the preparation of radioimmunoassay (RIA) reagents. 125I-rec-hGH was prepared by the classical chloramine-T iodination technique, while an internal standard of the same rec-hGH was used and calibrated against pituitary hGH reference preparation (NIDDK-hGH-RP-1) with the use of a reference antiserum (NIDDK-anti-hGH-2). In both cases the behavior of the recombinant preparation was identical to that of the pituitary hormone. This confirms previous data on bacterial correct processing and folding of the protein, as far as its immunological behavior is concerned and indicates its suitability for the preparation of immunoassay reagents.