Protein vs Species of Protein

Question

[nkhan.mscs15seecs]

In an article I am reading this line

"In DIP (Database of Interacting Protein) The 10,432 interacting pairs of protein consisted of 5849 species of Protein"

What does that mean?

My Understanding

Since one protein could interact with many other proteins that is why 5849 species of protein represents unique proteins?

Is that right?

[Joe]

It seems to me that that sentence actually tells you almost nothing about protein-protein interactions. I would assume that the proteins in that database are known to have at least 1 interaction, so yes, at least some of those 5849 have more than one interaction. If that isn't the case though, those 10,432 interactions could be made up of some proteins that don't interact with any other proteins, and some proteins that interact with lots of different ones.

Answer 1

[h.mon]

Protein species and the number of interactions are unrelated here. "Protein species" is a concept and term used in proteomics. It is fairly recent, apparently first used in Resolution power of two-dimensional electrophoresis and identification of proteins from gels. From the abstract of this technical paper:

Protein variants, which vary in their exact chemical composition, and which are coded by one gene or by a paralogous or orthologous gene or alleles of that gene, are called protein species. The term protein species covers splicing variants, truncated proteins and post-transla- tional modified proteins, and is defined chemically in contrast to the term isoform, which is defined genetically.