over 80 % of the proteins in the ciliary membrane belong to two groups : the immobilization antigen ( i-ag ) , which is a 220-280 kd surface protein , and a set of at least four integral proteins slightly over 40 kd ( the 40 k ) , most of which focus near ph 4.0 ( the acidic 40 k ) .
C0025252
surface protein
C0033684
proteins