<prompt> The transmembrane region of a protein is likely to haveA stretch of hydrophilic amino acidsA stretch of hydrophobic amino acidsA disulphide loopAlternating hydrophilic and hydrophobic amino acids  <response>: Some of the integral membrane proteins span the whole bilayer and they are called transmembrane proteins Fig. 2.4. The hydrophobic side chains of the amino acids are embedded in the hydrophobic central core of the membrane. The transmembrane proteins can serve as receptors for hormones, growth factors, neurotransmitters, tissue-specific antigens, ion channels, membrane-based enzymes, etc.Ref: DM Vasudevan, page no: 12 