Extracellular loop 3 substitutions K589N and A590S in FSH receptor increase FSH-induced receptor internalization and along with S588T substitution exhibit impaired ERK1/2 phosphorylation

- FSHR specific residues S588, K589 and A590 in EL3 of FSHR swapped with corresponding LH/CGR residues.
- FSH binding and cAMP production of EL3 mutants similar to wild type FSHR.
- K589N and A590S mutations contribute to increased internalization in triple mutant EL3M.
- FSH-induced ERK phosphorylation affected in all mutants and to most extent in A590S.