AF030: Papain-like cysteine protease

List allergens from this family:

Routes of exposure:
Include only IUIS approved allergens.

Biochemical properties

Members of the papain family are wide-spread in nature, having been found in baculovirus, bacteria, yeast, plants and animals. Despite structural similarities regarding the residues surrounding the catalytic site, the cysteine proteases have only low levels of overall sequence similarity [1]. Papain-like cysteine proteinases are synthesised as inactive proenzymes with N-terminal propeptide regions. The propeptide plays important roles as inhibitor of enzymatic activity and for the correct folding of the newly synthesized protein [2]. The mature enzymes are generally 25-28 kDa in size.

Allergens from this family

A number of allergens have been identified belonging to the papain family including group 1 mite allergens such as the major dust mite allergen Der p 1 [3] and food allergens such as actinidin, the major allergen from kiwifruit, bromelain from pineapple, ficin from fig and papain from papaya [1]. Gly m Bk30K (P34), a major allergen from soybean seed storage vacuoles, shows sequence similarity to papain-like proteases but lacks enzymatic activity [4].



  1. Mills EN, Jenkins JA, Alcocer MJ, Shewry PR:
    Structural, biological, and evolutionary relationships of plant food allergens sensitizing via the gastrointestinal tract.
    Crit Rev Food Sci Nutr 2004, 44, 379-407. [PubMed] [Full Text]
  2. Coulombe R, Grochulski P, Sivaraman J, Menard R, Mort JS, Cygler M:
    Structure of human procathepsin L reveals the molecular basis of inhibition by the prosegment.
    EMBO J 1996, 15, 5492-503. [PubMed]
  3. Thomas WR, Stewart GA, Simpson RJ, Chua KY, Plozza TM, Dilworth RJ, Nisbet A, Turner KJ:
    Cloning and expression of DNA coding for the major house dust mite allergen Der p 1 in Escherichia coli.
    Int Arch Allergy Appl Immunol 1988, 85, 127-9. [PubMed]
  4. Kalinski A, Weisemann JM, Matthews BF, Herman EM:
    Molecular cloning of a protein associated with soybean seed oil bodies that is similar to thiol proteases of the papain family.
    J Biol Chem 1990, 265, 13843-8. [PubMed]


Links to Pfam

Family-defining Pfam domains (at least one of these domains is present in each family member):

Pfam domain Pfam clan
PF00112 Papain family cysteine protease CL0125 Peptidase clan CA
PF08246 Cathepsin propeptide inhibitor domain (I29) -

Links to Wikipedia


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