Table 1. Clinical significance of naturally occurring point mutants of CFTR PTM sites.

Given are the residue, observed point mutation, and clinical significance of point mutations as reported in the CFTR mutation databases (30).

Modified peptide sequence	Site	A-score (−10×log(P))	Mutation in CF patients	Clinical significance
T*SNGDDSLFFSNFSLLGTPVLK	T421	19.21	T421A	CBAVD
GQLLAVAGSTGAGK(me)T	K464		K464N	CF, severe phenotype at early age with pancreatic insufficiency, chronic cough and bronchial infection, 3659delC mutation on the other chromosome (expected to lead to pancreatic insufficiency)
FAEK(ub)DNIVLGEGGITLSGGQR	K536		K536E	parent of a child with a positive newborn screening test
DNIVLGEGGITLS*GGQR	S549	64.79	S549N, S549I, S549F, S549R	CF, severe clinical phenotype
AVYK(ub)DADLYLLDSPFGYLDVLTEK	K564		K564E	CBAVD
NS*ILTETLHR	S660	56.02	S660T	asymptomatic
NSILTETHR(me)	R668		R668C	does not cause CF
LS*LVPDSEQGEAILPR	S737	94.12	S737F	elevated sweat chloride
LSLVPDSEQGEAILPR(me)I	R751		R751P, R751C, R751L	lung disease, carrier testing for R751C
VSLAPQANLTELDIYSR(me)R	R810		R810G	CBAVD (ΔF508 on other allele)
LS*QETGLEISEEINEEDLK	S813	69.89	S813P	very mild CF
AYFLQTSQQLK(ub)QLESEGR	K1041		K1081R	reduction of band C (McClure 2014)
TGSGK(ub)STLLSAFLR	K1250			K1250A mutation dramatically prolonged burst duration (abolishes ATP hydrolysis)