HORMONE/HORMONE RECEPTOR, COMPLEX, GLYCOPROTEIN, HORMONE, LACTATION, SECRETED, ALTERNATIVE SPLICING, MEMBRANE, RECEPTOR, TRANSMEMBRANE, HORMONE-HORMONE RECEPTOR COMPLEX THE 1:2 COMPLEX BETWEEN A NTERMINAL ELONGATED PROLACTIN AND THE EXTRA CELLULAR DOMAIN OF THE RAT PROLACTIN RECEPTOR 3EW3