Keith says no ste2 and ste3 in human cells; so Teresa offers specific
cite that states quite the opposite, at end of this post:
On 13 Mar 1996, Keith Robison wrote:
> : Teresa had written: The fact that
> : ste2 and ste3 are expressed in human T cells and perhaps elsewhere
> : suggests that there may be some aspect of preserved function.
>> Keith responded: No, Yeast ste2 and yeast ste3 are not expressed, but
> rather members of the GCR family.
The statement "Yeast ste2 and ste3 are not expressed" is interesting
given that it appears to directly contradict a published finding in the
cite hereinbelow. Of course, the human ste2 and ste3 may not be 100%
homologous, but in many instances that does deter from functional similarity.
Now, if Patel et al are using the symbols ste2 and ste3 for something
totally different from yeast ste2 and ste3, then that is an important
finding. Until we know that to be the case, the fact remains that Patel
et al report that ste2 and ste3 ARE expressed in humans.
> I am just pointing out that you need
> to provide more striking evidence (a GCR tree might do) for there
> being reason to expect that the yeast genes are functionally related to
> the human genes.
If findings reported in the cite hereinbelow are accurate, then the
evidence is, at least in an initial way, quite striking and suggests a
domain of overlooked research.
> A quick BLAST search with STE2 & 3 finds only
> other fungal GCRs; there is no special relationship to the
> T-cell proteins.
Perhaps BLAST is not as thorough as OVID access to medline. I'm not
familiar with BLAST but have used Paperchase extensively, and find OVID
preferable because it searches abstracts -- which is how I found one cite
documenting ste2 and ste3 in the human thymic epithelium.
The following cite contains in its abstract the finding the ste2 and ste3
were in fact found in cells from the human thymic epithelium; asterisks
are added to the left margin so as to indicate text-lines containing STE2
AU - Patel DD et al
TI - Characterization of human thymic epithelial cell surface antigens:
phenotypic similarity of thymic epithelial cells to epidermal
SO - Journal of Clinical Immunology 1995 Mar;15(2):80-92
AB - Cellular interactions between developing thymocytes and cells of the
thymic microenvironment are necessary for maturation of thymocytes
into mature T cells. While much is known about the molecules on
developing T cells that mediate these interactions, little is known
about the surface molecules of human thymic epithelial (TE) cells.
In this study, using a panel of 276 MAb including 255 MAb from the
5th International Workshop on Human Leukocyte Differentiation
Antigens (HLDA-V), we have determined the expression of CD1 through
CDw130 and other surface molecules on resting and
IFN-gamma-activated cultured human TE cells and on resting epidermal
keratinocytes (EK). We demonstrate the surface expression of 50 of
the 161 molecules assayed for on TE cells, including a number of
adhesion molecules, cytokine receptors, Apo-1, and MHC-encoded
molecules. While activation of TE cells with IFN-gamma for 48 hr
induced a greater than fivefold increase in the expression of four
surface molecules (CD38, CD54, MHC class I, and MHC class II), it
also induced a greater than 50% increase in the expression of 14
other surface molecules (CD12, CD29, CD40, CD44, CD47, CD49b, CD49c,
* CD49e, CD55, CD66, CD87, CD104, TE4, and STE3) and a decrease in the
* expression of three molecules (CDw65, CDw109, and STE2). In
comparing the phenotype of TE cells to 83 other cell lines studied
in HLDA-V, we found that TE cells were strikingly more similar to EK
than to any of the other cell types tested.
Teresa C. Binstock, Researcher
Developmental & Behavioral Neuroanatomy
Denver CO USA
Teresa.Binstock at uchsc.edu