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PR-B Isoform

Meaning

PR-B, or Progesterone Receptor B isoform, is the full-length protein variant transcribed from the progesterone receptor gene (PGR), containing all functional domains, including the critical N-terminal activation domain. It is generally considered the primary and most powerful transcriptional activator, mediating the classic proliferative and differentiation effects of progesterone in target tissues like the endometrium and breast. Its full activity is essential for the successful progression of the menstrual cycle and the maintenance of a healthy pregnancy.