Cloning and restriction fragment length polymorphism analysis of a cDNA for swine PIT‐1, a gene controlling growth hormone expression*

A partial swine cDNA which encodes the functional domain of PIT-1 was isolated by the polymerase chain reaction (PCR). The swine PIT-1 cDNA clone is 95% identical at the protein level to the rat Pit-1 gene. Thus, Pit-1's known function in control of rat growth hormone and prolactin expression is likely to be conserved in swine. This swine cDNA clone was used to investigate genetic variability at PIT-1 in several American and Chinese breeds. Polymorphic BamHI fragments were found in pure-bred Meishan animals (n = 13), but only monomorphic fragments in five American breeds (n = 36).