Populational change is Darwin’s hypothesis that evolution occurs by changes in the proportions (frequencies) of different variant kinds of individuals within a population.

TLS Online TPP Program

#Id: 9471

#XL - T Zoology

STAT5 becomes activated in erythroid progenitor cells and induces expression of the protein Bcl-xL.

TLS Online TPP Program

#Id: 9472

#XL - T Zoology

Two mechanisms for terminating cytokine signaling:

1. Short-term regulation: SHP1

2. Long-term regulation: SOCS proteins

TLS Online TPP Program

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#XL - T Zoology

SHP1 a phosphotyrosine phosphatase, contains:

SH2 domain  & Phosphatase domain

TLS Online TPP Program

#Id: 9474

#XL - T Zoology

SHP1 

Binding of an SH2 domain to a phosphotyrosine in the activated receptor unmasks its phosphatase catalytic site

TLS Online TPP Program

#Id: 9475

#XL - T Zoology

SHP1 causes removal of the phosphate from tyrosine in the activation loop of JAK2 & inactivates the JAK kinase.

TLS Online TPP Program

#Id: 9476

#XL - T Zoology

SOCS proteins 

expression is induced by the STAT5 in erythroid progenitor cells, inhibit or permanently terminate signaling over longer periods