FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * PERRIGO Co plc   2. Issuer Name and Ticker or Trading Symbol PROTEOSTASIS THERAPEUTICS, INC. [PTI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) TREASURY BUILDING, LOWER GRAND CANAL STREET 3. Date of Earliest Transaction (Month/Day/Year) 02/10/2016 (Street) DUBLIN, L2 2 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/17/2016   C   2,416,612 (1) A (1) 2,416,612 I See footnote (3) Common Stock 02/17/2016   C   366,455 (2) A (2) 2,783,067 I See footnote (3) Common Strock 02/17/2016   P   125,000 (4) A $ 8 2,908,067 I See footnote (3)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Series A Convertible Redeemable Preferred Stock

(1)

02/17/2016

C

20,000,000

(1)

(1)

Common Stock

2,416,612

$ 0

0

I

See footnote (3)

Series B Convertible Redeemable Preferred Stock

(2)

02/17/2016

C

3,961,459

(2)

(2)

Common Stock

366,455

$ 0

0

I

See footnote (3)

Stock Option (Right to Buy)

$ 8

02/10/2016

A

45,760

(5)

02/10/2016

Common Stock

45,760

$ 0

45,760

I

See footnote (6)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
PERRIGO Co plc TREASURY BUILDING LOWER GRAND CANAL STREET DUBLIN, L2 2		X
PERRIGO HOLDINGS LTD. TREASURY BUILDING, LOWER GRAND CANAL STREET DUBLIN, L2 2		X
ELAN PHARMA INTERNATIONAL LTD. TREASURY BUILDING, LOWER GRAND CANAL STREET DUBLIN, L2 2		X
PERRIGO CORP LTD. TREASURY BUILDING, LOWER GRAND CANAL ST DUBLIN 2, L2 2		X
PERRIGO SCIENCE ONE LTD. TREASURY BUILDING, LOWER GRAND CANAL STREET DUBLIN, L2 2		X

Signatures

/s/Todd Kingma, Secretary of Perrigo Company plc		02/18/2016
**Signature of Reporting Person		Date
/s/Todd Kingma, Secretary of Perrigo Holdings Ltd.		02/18/2016
**Signature of Reporting Person		Date
/s/Todd Kingma, Director of Elan Pharma International Limited		02/18/2016
**Signature of Reporting Person		Date
/s/Todd Kingma, Secretary of Perrigo Corporation Limited		02/18/2016
**Signature of Reporting Person		Date
/s/Todd Kingma, Secretary of Perrigo Science One Ltd.		02/18/2016
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	The Series A Convertible Redeemable Preferred Stock (the "Series A Shares") automatically converted on a 10.8102-to-1 basis into the Issuer's Common Stock, together with the accrued but unpaid dividends, upon closing of the Issuer's initial public offering into 2,416,612 shares of the Issuer's Common Stock. The Series A Shares did not have an expiration date.
(2)	The Series B Convertible Redeemable Preferred Stock (the "Series B Shares") automatically converted on a 10.8102-to-1 basis into the Issuer's Common Stock upon closing of the Issuer's initial public offering into 366,455 shares of the Issuer's Common Stock. The Series B Shares did not have an expiration date.
(3)	Perrigo Science One Ltd. ("Science") (formerly Elan Science One Ltd.) is the direct owner of these securities. Science is a direct or indirect, wholly-owned subsidiary of each of the other reporting persons.
(4)	These securities were purchased in connection with the initial public offering of the Issuer.
(5)	These securities shall vest and become exercisable in equal quarterly installments starting on February 10, 2016 until the option is fully vested and exercisable on February 10, 2019, subject to continued service.
(6)	Perrigo Company plc ("Perrigo") and the other reporting persons named herein may be deemed to beneficially own the 45,760 options granted to Mr. Walshe in his capacity as a director of Proteostasis Therapeutics, Inc. (the "Company"). Mr. Walshe has an understanding with Perrigo pursuant to which he holds such securities for the benefit of Perrigo.

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