Schematic comparison of natural and man-made hPRL receptor isoforms. EC domain, blue; TM domain, yellow; and IC domain, green. Long, long form of the hPRL receptor; intermed, intermediate form of the hPRL receptor; short 1a, short 1a form of the hPRL receptor; short 1b, short 1b form of the hPRL receptor; ΔS1, long form of the hPRL receptor with the S1 subdomain deleted; ΔS2, long form of the hPRL receptor with the S2 subdomain deleted; ECD, extracellular domain; ΔICD, long form of the hPRL receptor with the intracellular domain deleted; ΔECD, long form of the hPRL receptor with the extracellular domain removed; Δ10-186, long form of the hPRL receptor with residues 10-186 removed; I76V, long form of the hPRL receptor with isoleucine 76 replaced with valine; l146L, long form of the hPRL receptor with isoleucine 146 replaced with leucine.