The 4 subunits that make up an oocyte's zona peculida. Something seems to be up with the mRNA atlas entries for ZP3:r.
#ZP1, #ZP2, #ZP3, #ZP4 (zona pellucida glycoprotein 1, 2, 3 & 4): Human Protein Atlas Concensus mRNA tissue distributions & GPMDB protein tissue tabbulations. #proteomics



