pH Dependence of structural stability of interleukin-2 and granulocyte colony-stimulating factor.


After a cytokine binds to its receptor on the cell surface (pH approximately 7), the complex is internalized into acidic endosomal compartments (pH approximately 5-6), where partially unfolded intermediates can form. The nature of these structural transitions was studied for wild-type interleukin-2 (IL-2) and wild-type granulocyte colony-stimulating factor (G-CSF). A noncoincidence of denaturation transitions in the secondary and tertiary structure of IL-2 and tertiary structural perturbations in G-CSF suggest the presence of an intermediate state for each, a common feature of this structural family of four-helical bundle proteins. Unexpectedly, both IL-2 and G-CSF display monotonic increases in stability as the pH is decreased from 7 to 4. We hypothesize that such cytokines with cell-based clearance mechanisms in vivo may have evolved to help stabilize endosomal complexes for sorting to lysosomal degradation. We show that mutants of both IL-2 and G-CSF have differential stabilities to their wild-type counterparts as a function of pH, and that these differences may explain the differences in ligand trafficking and depletion. Further understanding of the structural changes accompanying unfolding may help guide cytokine design with respect to ligand binding, endocytic trafficking, and, consequently, therapeutic efficacy. Study holds ProTherm entries: 16246, 16247, 16248, 16249, 16250, 16251, 16252, 16253, 16254, 16255, 16256, 16257, 16258, 16259, 16260, 16261, 16262, 16263, 16264, 16265 Extra Details: protein folding; protein stability; equilibrium denaturation; folding intermediates;,endocytic trafficking; IL-2; G-CSF

Submission Details

ID: DAu82sJH4

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:47 p.m.

Version: 1

Publication Details
Ricci MS;Sarkar CA;Fallon EM;Lauffenburger DA;Brems DN,Protein Sci. (2003) pH Dependence of structural stability of interleukin-2 and granulocyte colony-stimulating factor. PMID:12717025
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
98.3 Granulocyte colony-stimulating factor P09919 CSF3_HUMAN
99.2 Interleukin-2 P60568 IL2_HUMAN
99.2 Interleukin-2 P60569 IL2_HYLLA
96.3 Interleukin-2 P68291 IL2_MACMU
96.3 Interleukin-2 P68290 IL2_MACNE
95.5 Interleukin-2 Q865Y1 IL2_PAPAN
95.5 Interleukin-2 P46649 IL2_CERAT
94.8 Interleukin-2 Q29615 IL2_MACFA
91.8 Interleukin-2 Q7JFM2 IL2_AOTLE
91.8 Interleukin-2 Q7JFM5 IL2_AOTNA
91.8 Interleukin-2 Q7JFM3 IL2_AOTNI
91.8 Interleukin-2 Q7JFM4 IL2_AOTVO
91.8 Interleukin-2 Q9XS38 IL2_PAPHA
91.0 Interleukin-2 Q8MKH2 IL2_SAISC
100.0 Granulocyte-macrophage colony-stimulating factor P04141 CSF2_HUMAN
94.4 Granulocyte-macrophage colony-stimulating factor Q0MUT8 CSF2_CHLAE