C1orf41 Conclusion
Our study have narrowed down to two possible functions of c1orf41. It can either be a small heat shock protein (sHsp) or a galactose binding protein. As mentioned earlier, c1orf41 is highly expressed in cancer cells. High expression of both sHsp and discoidin domain are observed in cancer cells.
In terms of sequence similarity, c1orf41 showed high sequence identity with other sHsps. Its sequence also showed the presence of alpha-B-crystallin domain typically found in sHsps. Although structure similarity search did not give sHsp as a result, alpha-B-crystallin domain is known to be made up of mainly beta-pleated sheet as observed in the structure of our protein. Previous studies have shown that c1orf41 is an intracellular protein, which is where sHsps are located. In addition to that the structure of c1orf41 indicated that Ca2+ might be important for its function as shown by previous studies.
Based on the structure of c1orf41, Dali and Pfam result showed that this protein consists of a discoidin (F5/8 C type) domain and its structure has high structural similarities with proteins having galactose binding function. The presence of the loop and a metal ion coordinated within the loop is also observed in the proteins from the DALI result. However, our protein does not have the motif that is essential for galactose binding. The F5/8 C type domain is also known to function in cell adhesion. Again, the motif that is present in cell adhesion proteins was not observed in our protein. In addition to that, F5/8 C type domain are generally extracellular or membrane proteins. But, it is known that our protein is found inside the cell and its structure does not indicate that it is a membrane protein.
In conclusion, compared to being a galactose binding protein, there are more information indicating that c1orf41 is a sHsp.
