The DSEF-1 Protein

Computer Predicted RRMs and Auxiliary Domains of the DSEF-1 protein

DSEF-1 is a member of hnRNP H family of proteins

Computer-Predicted RNA Recognitiom Motifs (RRMs) and Glycine-Rich Auxiliary Domains in the  DSEF-1  protein

The DSEF-1 protein is 449 amino acids long. Computer based structure predictions and comparison of the primary amino acid sequence with closely related proteins suggests the presence of three RNA Recognition Motifs (RRMs) and two glycine-rich Auxiliary Domains in the DSEF-1 protein.

DSEF-1 is a member of hnRNP H family of proteins:

The DSEF-1 protein bears a very close similarity to hnRNP H (96.2 % identity) and hnRNP F(75.4 % identity) and is identical to hnRNPH’, a variant of hnRNP H. Interestingly, all of these proteins are also known to bind poly(G) RNA sequences (e.g. GRS). DSEF-1 is considered a member of this family of proteins.

Computer-Predicted RNA Recognitiom Motifs (RRMs) and  Auxiliary Domains in the  DSEF-1  protein in comparison with other RNA-binding proteins which also bind preferentially to G-rich sequences. The numbers represent amino acid positions relative to the amino terminus.

GRSF-1, another RNA-binding protein that also specifically recognizes G-rich sequences, exhibits 43.4% identity (53.3% similarity) to DSEF-1. However, its RRM sequence alignment with hnRNP H family members reveals a close relationship of GRSF-1 with this family of poly(rG) binding proteins.

A strikingly close similarity between RRMs of the hnRNP H protein family, suggests conservation of RRM structure and, thus, a possible evolutionary significance. The conservation of structure, in turn, may suggest a conservation of function as well. Therefore, comparison of predicted structure of DSEF-1 with close relatives of its family should provide clues to correlated functions.

Common property of all the members of this family is that they bind to poly(G) or G-rich RNA sequences. Thus, sequence conservations, especially in RRMs, unique to these proteins are likely to be correlated to their common RNA-binding specificities. On the other hand, differences in their sequences might reflect differences in the functions of these closely related proteins.

Sequence alignment of the RRMs of this hnRNP H protein family also reveals sequences that are uniquely conserved (other than RNP motifs) only in these proteins and thus might have evolutionary significance (Bagga et. al, 1998). The conservation of these regions is likely to be a reflection of conserved function among the hnRNP H family proteins.