Calreticulin-3 (CALR3)

Calreticulin-3 (CALR3) is an endoplasmic reticulum-resident chaperone protein, specifically expressed during spermatogenesis in the testis where it functions in protein folding and quality control as a lectin-independent chaperone for certain client proteins, including ADAM3[4]. CALR3 is critical for sperm maturation and male fertility[4][5]. It is part of the cancer/testis antigen family, meaning it has highly restricted normal tissue expression but may be aberrantly expressed in some cancers, making it a potential target for cancer immunotherapy[5]. CALR3's main biological role is providing chaperone support for sperm functional proteins, distinct from classical calreticulin (CALR). No direct drugs currently target CALR3, but it remains an area of active research for fertility treatments and tumor immunology. CALR3 should not be confused with CALR (calreticulin 1), which has wider expression and disease roles. The CRT2 alias is shared with "calreticulin-2" and may cause confusion; for cancer/testis antigen research, "calreticulin-3 (CALR3)" is the recommended nomenclature.

Other names

Calreticulin-3CALR3CRT2FLJ25355MGC26577CT93Cancer/testis antigen 93CalsperinTestis secretory sperm-binding protein Li 226nCMH19

Experimental cancer immunotherapies may aim to elicit an immune response against CALR3-expressing cells (cancer/testis antigens are attractive due to restricted normal tissue expression).