The domain within your query sequence starts at position 27 and ends at position 138; the E-value for the IL3 domain shown below is 3.8e-41.

ASISGRDTHRLTRTLNCSSIVKEIIGKLPEPELKTDDEGPSLRNKSFRRVNLSKFVESQG
EVDPEDRYVIKSNLQKLNCCLPTSANDSALPGVFIRDLDDFRKKLRFYMVHL

IL3

IL3
PFAM accession number:PF02059
Interpro abstract (IPR002183):

Interleukin-3 (IL3) is a cytokine that regulates blood-cell production by controlling the production, differentiation and function of granulocytes and macrophages [ (PUBMED:3497843) (PUBMED:2413359) ]. The protein, which exists in vivo as a monomer, is produced in activated T-cells and mast cells [ (PUBMED:3497843) (PUBMED:2413359) ], and is activated by the cleavage of an N-terminal signal sequence [ (PUBMED:2413359) ].

IL3 is produced by T-lymphocytes and T-lymphomas only after stimulation with antigens, mitogens, or chemical activators such as phorbol esters. However, IL3 is constitutively expressed in the myelomonocytic leukaemia cell line WEHI-3B [ (PUBMED:2413359) ]. It is thought that the genetic change of the cell line to constitutive production of IL3 is the key event in development of this leukaemia [ (PUBMED:2413359) ].

GO process:immune response (GO:0006955)
GO component:extracellular region (GO:0005576)
GO function:interleukin-3 receptor binding (GO:0005135), growth factor activity (GO:0008083)

This is a PFAM domain. For full annotation and more information, please see the PFAM entry IL3