The nucleotide and partial amino acid sequences of rat fetuin

Fetuins are among the major plasma proteins, yet their biological
role has remained elusive. Here we report the molecular cloning of
rat fetuin and the sequence analysis of a full-length clone, RF619
of 1456 bp with an open reading frame of 1056 bp encoding 352 amino
acid residues. The coding part of RF619 was identical with the cDNA
sequence of the natural inhibitor of the insulin receptor tyrosine
kinase from rat (pp63) except for four substitutions and a single
base insertion causing divergence of the predicted protein
sequences. Partial amino acid sequences of rat plasma fetuin were
in agreement with the predictions based on the RF619 cDNA. Purified
rat fetuin inhibited the insulin receptor tyrosine kinase in vitro.
Therefore, we conclude that RF619 and pp63 cDNA encode the same
protein, i.e. authentic rat fetuin which is a functional tyrosine
kinase inhibitor.