It exists only one GFP. Variants and other autofluorescing proteins have their own names e.g.YFP or mCherry and should be cited according to thei first desciption. ´GFP-lke or GFP-type , for my opoinion, should not be used.

Best,

Guenther

Even more complications:  the term "related protein" is also used in naming proteins and there is no rule as yet to standardize the nomenclature as with IUPAC or in enzymology.  For now it seems function is used for "like" ; IGF-1 for example is called insulin like growth factor 1 but doesn't have the amino acid homology to insulin.  I think "type may refer more to amino acid homology.  Terminology dilemmas exists everywhere in biology and biochemistry, paralogue and orthologue for example, but for now people will need to define their terms and editors/reviewers will need to enforce it.  

The original green-fluorescent protein was isolated from Aequorea victoria, a homologous red fluorescent protein was found in Discosoma corals. Natural homologs are likely to be found in related organisms. Since the discovery of the original GFP, protein engineering has been used to improve the stability, folding properties, fluorescence quantum yield  and spectrum of both GFP and RFP. Other natural homologs share the fold of GFP but have other functions. http://mbe.oxfordjournals.org/content/21/5/841.full . GFP-like molecules are sequence and structural homologs of GFP, both natural and artificial.

Grant Shimamoto: Insulin-like growth factors IGFI and IGFII both not only have marked sequence homology to insulin, but also crossreact with the insulin receptor. Upon discovery, they were called "NSILA", non-supressable insulin-like activity, since they did elicit insulin like effects in cells and animals that could not be blocked by neutralizing antibodies against insulin. After the proteins had been characterized, they were renamed insulin-like growth factors since they are members of the insulin family, but their primary physiological role was found to be growth regulation (somatomedin) rather than metabolic regulation.

XXX-like is often used to describe genes/proteins that have clear sequence homology to gene XXX, but have not yet been characterized well enough to tell whether they are orthologs of XXX, or paralogs that may have a similar structure but a different function.

Sorry for cut/paste error.  Should read "and does have".  The "but doesn't have" referred to the cleavage site between chains.  A reference which seems to help with the orthologue - paralogue explanation could be helpful:  Genome Biol. 2001; 2(8): interactions1002.1–interactions1002.3.

Published online 2001 Aug 3.

PMCID: PMC138949

Orthologs and paralogs - we need to get it right

Roy A Jensencorresponding author1

In the case of fluorescent proteins, commercial interests play a role: the blue to yellow range of the spectrum of commercial fluorescent proteins is covered by proteins derived from the original GFP, the red by derivative from RFP. For most other proteins, we biochemists would usually not give a different name for variants of a protein generated in the lab, and species variation would be covered by adding the species name to the name of the protein (e.g. bovine insulin vs. human insulin). Since the GFP variants are marketed for a specific purpose, and that purpose depends on their spectral properties, "Trademark" names have been applied to these proteins. On the other hand, a bioinformatician trying to make sense of the genetic sequences of marine organisms would annotate as "GFP-like" any gene with high enough sequence homology to GFP what has not been given a different mane yet. As my previous cite shows, a superfamily is being defined that comprises proteins that fold in the GFP fold, and is subdivided into families that have features in common.

Normally, "GFP-like" is used for anything that in sequence and structure is similar to GFP ( 27'700 Google hits), even if it shows no fluorescence , while "GFP-type" (3'430 google hits, many of these relating to unrelated topics such as "ground fault protector") is a less defined expression that is predominantly use to describe functional similarity, e.g. in the expression of "GFP-type chromophore"