Symbol CH2 PDB 1PUO | Entrez 677879 UniProt P30440 | |
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Alt. symbols Fel d I, AG4, Allergen Cat-1 | ||
Fel d 1 is a protein that in cats is encoded by the CH1 (chain 1/Fel d 1-A) and CH2 (chain 2/Fel d 1-B) genes.
Fel d 1, produced largely in cat saliva and sebaceous glands, is the primary allergen present on cats and kittens. Fel d 1 is also produced by cat skin itself. The protein is of an unknown function to the animal but causes an IgG or IgE reaction in sensitive humans (either as an allergic or asthmatic response). Removal of soft surfaces in the home (carpet, furniture), frequent washings of bed linens, HEPA filters and even washing cats has been proven to reduce the amounts of Fel d 1 present in the home.
Female cats produce a lower level of Fel d 1 than males, and neutered males produce a lower level of Fel d 1 than unneutered males.
Neutered males produce Fel d 1 in levels similar to females (both intact and spayed females produce Fel d 1 in similar levels). Even though females and neutered males produce Fel d 1 in lower levels, they still produce enough to cause allergic symptoms in sensitive individuals.
Structure
The complete quaternary structure of Fel d 1 has been determined. The allergen is a tetrameric glycoprotein consisting of two disulfide-linked heterodimers of chains 1 and 2. Fel d 1 chains 1 and 2 share structural similarity with uteroglobin, a secretoglobin superfamily member; chain 2 is a glycoprotein with N-linked oligosaccharides. Both chains share an all alpha-helical structure.